And that brings the action right here to a close as well after that opening day.
Don't forget - you can read full close of play reports on all of the fixtures on the BBC Sport website and app right here.
We'll of course be back for live text and radio coverage of the second day's play on Friday from around 10:45 BST.
Until then - thanks for being with us at the start of a new season. It's great to be back!
Close of play scores
Rex FeaturesCopyright: Rex Features
Group 1
Essex 207-3 v Worcestershire
Nottinghamshire v Durham 241-7
Warwickshire 13-1 v Derbyshire 189
Group 2
Gloucestershire v Surrey 220-9
Leicestershire v Hampshire 431-4
Middlesex 293-8 v Somerset
Group 3
Northamptonshire v Kent 309-7
Lancashire v Sussex 291-9
Yorkshire v Glamorgan 310-8
Post update
And that's all the action done and dusted for this first day, stay right there and we'll show you how all the matches stand....
Stumps at Headingley
Yorkshire v Glamorgan 310-8
And a fantastic day's entertainment comes to an end at Headingley.
A superb fightback from Glamorgan sees them close on 310-8 having been reduced to 132-7 midway through the afternoon session.
Timm van der Gugten is unbeaten on 80 while Michael Hogan will resume on 40 tomorrow.
Ben Coad took 3-79 to be the pick of Yorkshire's bowlers.
Close of play at Lord's
Middlesex 293-8 v Somerset
Somerset's session.
Lewis Gregory got the big wicket of Sam Robson for 165 as Somerset claimed four wickets after tea.
Middlesex are still in a decent position, but the game is just about in the balance.
Stumps at Leicestershire
Leics v Hants 431-4
A day of utter dominance by Hampshire's batsmen is brought to a close.
James Vince goes to stumps on 168 off 167 balls.
Tom Alsop also made a century earlier.
Glamorgan pass 300
Yorkshire v Glamorgan 308-8
Still two overs to bowl at Headingley at the end of this fascinating first day.
This situation seemed unthinkable when Glamorgan were reduced to 132-7. They're now 308-8 as Michael Hogan (39 not out) and Timm van der Gugten (79 not out) continue to flay the bowling to all parts.
Close of play at Edgbaston and Northampton
Two more games done for the day.
In Group 1, they didn't get back on again after that bad light delay at Edgbaston where Warwickshire closed on 13-1 in reply to Derbyshire 189.
At Northampton, Kent reached 309-7 at stumps in that Group 3 encounter.
Evergreen Darren Stevens will resume on 34 on Friday after half-centuries from Ollie Robinson (84), Jack Leaning (79) and Jordan Cox (62) earlier on.
Somerset fight back
Middlesex 291-8 v Somerset
Kevin Hand
BBC Radio London at Lord's
Lewis Gregory has led the fightback for Somerset with the
second new ball - including finally removing Sam Robson.
Having been dropped at first and second slip before reaching
fifty, Robson eventually as he tried to guide the ball to third man but only picked
out third slip.
Middlesex now face a scramble to the third batting point -
which would be a blow to miss out on given one man made 165. With the
floodlights on for the most part since the evening session began its added an
extra bit of zip to processings.
Glamorgan run fest continues
Yorkshire v Glamorgan 292-8
Runs, runs and more runs from the Glamorgan lower order as we move towards the close of the day at Headingley.
Michael Hogan has picked up where Dan Douthwaite left off earlier and already has a run-a-ball 26 while Timm van der Gugten shows no signs of easing up on 77 not out.
It's now his first-class career best knock.
Close of play at Trent Bridge
Nottinghamshire v Durham 241-7
All 96 overs of the day's allocation bowled at Trent Bridge where Durham close on 241-7.
Brydon Carse (21 not out) and Ben Raine (20 not out) have added 45 for the eighth wicket so far to hold up the charge of the Notts bowlers.
Earlier in the day there were half-centuries for both Alex Lees (58) and David Bedingham (57) while Jack Burnham also made 42.
Bad light stops play at Edgbaston (again!)
Warwickshire 13-1 v Derbyshire 189
And they're also off in Birmingham.
Might not be completely done for the day as both sets of players have decided to take some seats just the other side of the boundary rope and the two umpires have stayed out there in the middle for now.
Bad light stops play again!
Essex 207-3 v Worcestershire
And after just seven more balls, they're off again at Chelmsford.
That looks pretty decisive as well from umpires Millns and Mallender. It doesn't look like it's improved anywhere near enough to get out there again.
WICKET
Helm c Hildreth b Gregory 9 (Middlesex 281-8 v Somerset)
A fourth wicket for Lewis Gregory as Somerset continue their evening session fightback.
Tom Helm prods forward and edges to first slip where James Hildreth takes a good low catch.
Seamer Gregory has 4-56.
Get Involved
Tweet us using #bbccricket
Flat Track Bully: Cox, Leaning & Robinson all could've had three figures for Kent today.
Ollie Robinson has just been dismissed for 84 by Northants to go with Cox's 62 and Leaning's 79. Kent are 296-6.
Bears lose early wicket
Group 1 update
Meanwhile back at Edgbaston, Warwickshire made a far from ideal start to their reply against Derbyshire.
Skipper Will Rhodes fell from the second ball of the innings without scoring leg before to Sam Conners.
They're now 13-1 with England opener Dom Sibley on three and Rob Yates on 10.
At Trent Bridge, Durham are hanging in there at 228-7. Brydon Carse and Ben Raine hanging around having added 32 for the eigth wicket so far.
Resumption at Chelmsford
Essex 206-3 v Worcestershire
And in news I wasn't expecting to report - they're coming back out again at Chelmsford.
Five overs lost from that bad light interruption as Tom Westley (84 not out) and Paul Walter (26 not out) resume for the hosts.
WICKET
Haines c Davies b Bailey 155 (Lancashire v Sussex 277-8)
Tom Haines' mammoth career-best knock is finally ended late in the day at Old Trafford.
The 22-year-old Sussex opener edges Tom Bailey behind for a terrific 155.
Post update
Leics v Hants 405-4
Maximum batting bonus points for Hampshire as they go past 400.
Liam Dawson has joined James Vince in the boundary-fest, moving to 29 off 26 balls with six fours.
Vince has 165 at better than a run a ball.
WICKET
Douthwaite b Coad 57 (Yorkshire v Galmorgan 254-8)
And the Glamorgan fun and games finally come to an end between Dan Douthwaite and Timm van der Gugten.
Douthwaite is bowled by Ben Coad for 57 as he was caught in two minds not really knowing whether to play or leave. He does neither convincingly and Coad makes the breakthrough finding middle and off stump.
That ends a fantastic partnership of 122 for the eighth wicket.
Live Reporting
Adam Williams and Gary Smee
All times stated are UK
PA MediaCopyright: PA Media 
Rex FeaturesCopyright: Rex Features 
Latest PostAnd that's a wrap
And that brings the action right here to a close as well after that opening day.
Don't forget - you can read full close of play reports on all of the fixtures on the BBC Sport website and app right here.
We'll of course be back for live text and radio coverage of the second day's play on Friday from around 10:45 BST.
Until then - thanks for being with us at the start of a new season. It's great to be back!
Close of play scores
Group 1
Essex 207-3 v Worcestershire
Nottinghamshire v Durham 241-7
Warwickshire 13-1 v Derbyshire 189
Group 2
Gloucestershire v Surrey 220-9
Leicestershire v Hampshire 431-4
Middlesex 293-8 v Somerset
Group 3
Northamptonshire v Kent 309-7
Lancashire v Sussex 291-9
Yorkshire v Glamorgan 310-8
Post update
And that's all the action done and dusted for this first day, stay right there and we'll show you how all the matches stand....
Stumps at Headingley
Yorkshire v Glamorgan 310-8
And a fantastic day's entertainment comes to an end at Headingley.
A superb fightback from Glamorgan sees them close on 310-8 having been reduced to 132-7 midway through the afternoon session.
Timm van der Gugten is unbeaten on 80 while Michael Hogan will resume on 40 tomorrow.
Ben Coad took 3-79 to be the pick of Yorkshire's bowlers.
Close of play at Lord's
Middlesex 293-8 v Somerset
Somerset's session.
Lewis Gregory got the big wicket of Sam Robson for 165 as Somerset claimed four wickets after tea.
Middlesex are still in a decent position, but the game is just about in the balance.
Stumps at Leicestershire
Leics v Hants 431-4
A day of utter dominance by Hampshire's batsmen is brought to a close.
James Vince goes to stumps on 168 off 167 balls.
Tom Alsop also made a century earlier.
Glamorgan pass 300
Yorkshire v Glamorgan 308-8
Still two overs to bowl at Headingley at the end of this fascinating first day.
This situation seemed unthinkable when Glamorgan were reduced to 132-7. They're now 308-8 as Michael Hogan (39 not out) and Timm van der Gugten (79 not out) continue to flay the bowling to all parts.
Close of play at Edgbaston and Northampton
Two more games done for the day.
In Group 1, they didn't get back on again after that bad light delay at Edgbaston where Warwickshire closed on 13-1 in reply to Derbyshire 189.
At Northampton, Kent reached 309-7 at stumps in that Group 3 encounter.
Evergreen Darren Stevens will resume on 34 on Friday after half-centuries from Ollie Robinson (84), Jack Leaning (79) and Jordan Cox (62) earlier on.
Somerset fight back
Middlesex 291-8 v Somerset
Kevin Hand
BBC Radio London at Lord's
Lewis Gregory has led the fightback for Somerset with the second new ball - including finally removing Sam Robson.
Having been dropped at first and second slip before reaching fifty, Robson eventually as he tried to guide the ball to third man but only picked out third slip.
Middlesex now face a scramble to the third batting point - which would be a blow to miss out on given one man made 165. With the floodlights on for the most part since the evening session began its added an extra bit of zip to processings.
Glamorgan run fest continues
Yorkshire v Glamorgan 292-8
Runs, runs and more runs from the Glamorgan lower order as we move towards the close of the day at Headingley.
Michael Hogan has picked up where Dan Douthwaite left off earlier and already has a run-a-ball 26 while Timm van der Gugten shows no signs of easing up on 77 not out.
It's now his first-class career best knock.
Close of play at Trent Bridge
Nottinghamshire v Durham 241-7
All 96 overs of the day's allocation bowled at Trent Bridge where Durham close on 241-7.
Brydon Carse (21 not out) and Ben Raine (20 not out) have added 45 for the eighth wicket so far to hold up the charge of the Notts bowlers.
Earlier in the day there were half-centuries for both Alex Lees (58) and David Bedingham (57) while Jack Burnham also made 42.
Bad light stops play at Edgbaston (again!)
Warwickshire 13-1 v Derbyshire 189
And they're also off in Birmingham.
Might not be completely done for the day as both sets of players have decided to take some seats just the other side of the boundary rope and the two umpires have stayed out there in the middle for now.
Bad light stops play again!
Essex 207-3 v Worcestershire
And after just seven more balls, they're off again at Chelmsford.
That looks pretty decisive as well from umpires Millns and Mallender. It doesn't look like it's improved anywhere near enough to get out there again.
WICKET
Helm c Hildreth b Gregory 9 (Middlesex 281-8 v Somerset)
A fourth wicket for Lewis Gregory as Somerset continue their evening session fightback.
Tom Helm prods forward and edges to first slip where James Hildreth takes a good low catch.
Seamer Gregory has 4-56.
Get Involved
Tweet us using #bbccricket
Flat Track Bully: Cox, Leaning & Robinson all could've had three figures for Kent today.
Ollie Robinson has just been dismissed for 84 by Northants to go with Cox's 62 and Leaning's 79. Kent are 296-6.
Bears lose early wicket
Group 1 update
Meanwhile back at Edgbaston, Warwickshire made a far from ideal start to their reply against Derbyshire.
Skipper Will Rhodes fell from the second ball of the innings without scoring leg before to Sam Conners.
They're now 13-1 with England opener Dom Sibley on three and Rob Yates on 10.
At Trent Bridge, Durham are hanging in there at 228-7. Brydon Carse and Ben Raine hanging around having added 32 for the eigth wicket so far.
Resumption at Chelmsford
Essex 206-3 v Worcestershire
And in news I wasn't expecting to report - they're coming back out again at Chelmsford.
Five overs lost from that bad light interruption as Tom Westley (84 not out) and Paul Walter (26 not out) resume for the hosts.
WICKET
Haines c Davies b Bailey 155 (Lancashire v Sussex 277-8)
Tom Haines' mammoth career-best knock is finally ended late in the day at Old Trafford.
The 22-year-old Sussex opener edges Tom Bailey behind for a terrific 155.
Post update
Leics v Hants 405-4
Maximum batting bonus points for Hampshire as they go past 400.
Liam Dawson has joined James Vince in the boundary-fest, moving to 29 off 26 balls with six fours.
Vince has 165 at better than a run a ball.
WICKET
Douthwaite b Coad 57 (Yorkshire v Galmorgan 254-8)
And the Glamorgan fun and games finally come to an end between Dan Douthwaite and Timm van der Gugten.
Douthwaite is bowled by Ben Coad for 57 as he was caught in two minds not really knowing whether to play or leave. He does neither convincingly and Coad makes the breakthrough finding middle and off stump.
That ends a fantastic partnership of 122 for the eighth wicket.