Marsh sends down four innocuous deliveries that Cook just nudges away.

The tired Aussie fielders finally jog in, trying to stop Cook picking up the single that will return him to the strike tomorrow morning.

Cook isn't fazed - instead driving Marsh deliciously through cover for four. That takes him past Brian Lara into sixth in the all-time ranking for Test runs. He's surpassed some fine players in this innings.

He drives the final ball of the day to mid-off for no run. Well played that man.

Image source, PA

Mitchell Marsh will continue, with what may well be the final over of the day...

James Anderson digs out a couple of deliveries from Bird, before doing well not to edge an ugly poke at a short ball.

A thick inside edge onto the pad next - Bird appeals but umpire Ravi shakes his head and Anderson shakes the bat, both signalling the number 11 hit it.

A loose ball down leg evades everything before Anderson blocks the last on the front foot.

Simon Smith, Harrogate.

Mitchell Marsh is back on - no danger for Alastair Cook, who is still turning down singles.

He'll take boundaries though - Marsh offering width and Cook scything him away via a thickish edge to the fence.

Ten minutes until the close, but if the final wicket falls now, that will be the end of the day.

Cook can't pick a single off the last, leaving Anderson to face next up.

Andrew Samson
BBC Test Match Special statistician

Cook has now batted for 10 and a half hours. He joins Mahela Jayawardene as the only Test player to have played four Test innings of 10 hours or more.

Nathan Lyon has a whole over to go at James Anderson - and does nothing with it, England's number 11 calmly playing out a maiden.

Cook is now closing in on Brian Lara's tally for Test runs.

Andrew Samson
BBC Test Match Special statistician

This is Cook's highest score against Australia now, passing his previous best of 235 not out in Brisbane in 2010.

It means that Alastair Cook, having started the innings with only 83 runs in the series, is now England's leading run scorer in the series.

Cook was happy to take ones and trust Broad with the strike - not so with Anderson as the opener turns down two singles from the first two balls of the over.

Make that three dots from three as Cook pulls to deep square leg and says no. And again to deep mid-off.

Cook flashes and gets a thickish edge that flies past the diving Khawaja at gully to the fence.

A single to keep the strike? No - Cummins offers width and Cook deftly cuts it away for a second straight boundary.

Peter Mounstephen: How could the on-field umpires possibly give a soft dismissal opinion on that? They couldn’t have seen a thing

MFG: Even from Toronto I could see that was not a catch!

Lallanarama: Been a shocker for the umpires this innings.

So around 20 minutes left to play on day three. Can James Anderson hang around with Alastair Cook?

He does for now, blocking three balls from Lyon after Cook picked up another single.

If you've just been startled by your alarm, you haven't woken up in 2010 - Alastair Cook has another Ashes double century.

He has batted all day with wickets falling around him and is batting England into a very strong position and a lead of way over 100.

Earlier Joe Root failed to press on after reach his fifty and Dawid Malan, Jonny Bairstow and Moeen Ali were out in the 20s.

Cook has been helped greatly by the lower order and in particular Stuart Broad. The pair shared a hundred partnership with Broad making a rare Ashes half-century.

Broad has just finally fallen in controversial fashion with confusion as to whether Usman Khawaja held on to a catch in the deep but Cook is now in the middle with James Anderson as the lead closes on 150.

After all that kerfuffle, Cook takes a single from the last ball of the over to keep new man James Anderson away from the strike.

Graeme Swann
Ex-England spinner on BBC Test Match Special

That is an incredible decision. If you are English you see that and think there is no way that is out. If you Australian you say that is definitely out.

Stuart Broad has put his helmet back on.

The Aussie fans cheer the replay, thinking it confirms Broad is out.

The Barmy Army cheer the replay, thinking it confirms Khawaja has spilled it.

Michael Vaughan
Ex-England captain on BBC Test Match Special

The soft signal is out. There has to be enough evidence to overturn that. I think that is out.

Hmmm. Khawaja took it at first but the ball looks to pop back out of his hands. Did he gather it again before it grazed the turf?

Usman Khawaja looks to have taken a fine low catch running in from the fence to remove Stuart Broad.

Broad isn't sure and the umpires have sent it upstairs. The soft signal is out...

See ball, hit ball for Broad now as he's back and pulling Cummins away for another four.

Nathan Lyon misreads the flight and ends up running under it.