Constituency changes: The implications

England, Scotland and Wales and Northern Ireland could all see their parliamentary representation reduced after the next general election, due in May 2015. With details for England and Northern Ireland's proposed constituency changes being published first, the BBC's network of regional political editors have been analysing what it will mean at local level. Details for Wales and Scotland will be published at a later date.

South West of England, political editor Martyn Oates

Under the Boundary Commission's plans, the new seat of Bideford and Bude would include Bude, Launceston and Camelford in Cornwall plus Bideford, Holsworthy and Torrington in Devon.

The Boundary Commission has chosen to cross the Cornwall/Devon border in the shallow upper reaches of the Tamar.

It clearly hopes this will be less controversial than doing so in the shadow of Brunel's famous bridge at the iconic mouth of the estuary [near Plymouth].

But is a less impressive boundary necessarily less important to people?

The border will only be breached through a tiny bottleneck in the north.

But this would still mean a great chunk of Cornwall - including the county's ancient capital with the castle of the Earls of Cornwall, Launceston - being forced into a union with towns deep into Devon.

Under the new law on constituency sizes, though, the Boundary Commission says Cornwall will inevitably have to share an MP with Devon in some way, shape or form.

South of England, Political Editor Peter Henley

In some parts of the south of England it was a breeze. Berkshire recently had a series of boundary changes so Maidenhead, Bracknell, Wokingham, Reading lined up - bang, bang, bang - with their 76,000 electorate.

Surrey, Buckinghamshire and Oxfordshire too got through with a tweak here and there.

But Hampshire, oh dear. And in Sussex, too - rather like the tail end of the crossword - nothing seemed to fit.

So Chris Huhne sees his Eastleigh stronghold carved four ways, though local Lib Dem support could carry him through, all other things being equal.

George Hollingbery's new seat of Meon Valley is gone - on the principle perhaps of last in, first out. There's a new seat of Hedge and Hamble and Romsey joins back up with the New Forest Waterside, leaving Caroline Nokes high and dry.

Add to that splitting Portsmouth East/West rather than North/South and you have to wonder if someone in the Boundary Commission had it in for Hampshire.

Brighton sees Transport Minister Norman Baker bussed in to the east from more comfortable Lewes, whilst on the west Hove is mixed up with the Pavilion constituency that gave the Green Party leader Caroline Lucas her historic first seat.

With the Greens now running the council they may well be extending their influence, but it will take time for people to work out the overall dynamic.

In the South West Robert Walter's North Dorset seat disappears - 43.9% of it is in with the Warminster and Shaftesbury seat, along with 46% of South West Wiltshire and a little bit of Devizes and Salisbury for good measure.

London, political editor Tim Donovan

The case of Tessa Jowell epitomises the kind of dilemma which could face many politicians at the next election. The former Olympics minister's south London seat is one of the most high-profile 'casualties' of the planned reshaping of the capital's electoral landscape.

The constituency of West Norwood and Dulwich will be chopped up into three pieces, with 40% of the electorate becoming part of a new Brixton seat, 35% going to a new seat of Dulwich and Sydenham, and the remaining part becoming part of the new Streatham and Tooting.

Which seat should Ms Jowell try to contest next time? Opt for leafy Sydenham and keep her association with Dulwich? Or strike out for the inner-city heartland of Brixton, likely to be a safer bet for a Labour win?

Her fortunes now become potentially entwined with Streatham's man-in-a-hurry Chuka Umunna whose own seat is being carved up into four. He might find himself fighting her for Brixton or contemplating a tussle with his Tooting neighbour, shadow justice secretary Sadiq Khan, for the newly created Streatham and Tooting berth.

Several similar battles may lie ahead as the current 73 constituencies are cut by five. Only four London seats - Bethnal Green and Bow, Chipping Barnet, Hendon and Poplar and Limehouse - would face no change to their boundaries.

Among the government ministers most affected will be Work and Pensions Secretary Iain Duncan-Smith, whose Chingford and Woodford Green seat will be split in three, and the Lib Dems' Vince Cable.

And after being partnered with Westminster for more than half a century - continuously Conservative - the City of London would be combined with Islington South, currently held by Labour's Emily Thornberry.

East Midlands, political editor John Hess

Both the Justice Secretary Ken Clarke and Labour's Vernon Coaker face an uncertain future if their Nottinghamshire constituencies are abolished.

In the Conservative stronghold of Rushcliffe, Trent Bridge historically and traditionally has been the dividing line between city and county. But under the Boundary Commission's proposals, the Rushcliffe constituency would be abolished and West Bridgford and great swathes of Rushcliffe's leafy suburbia would go into Nottingham South, currently Labour held. And it's not the only surprise.

The number of constituencies in the East Midlands would be cut from 46 to 44. Derbyshire loses a seat as two constituencies - Amber Valley and Mid Derbyshire - are merged. That's means the current MPs - Pauline Latham and Nigel Mills, who were both elected for the first time in the last election - will have to compete for the new seat.

Back in Nottinghamshire and Mr Clarke's Rushcliffe is parcelled out three ways to Newark, Nottingham South and a new constituency of Keyworth and Coalville in Leicestershire.

Mr Coaker's Gedling is also abolished with wards going into a redrawn Nottingham East, currently represented by Labour's Chris Leslie.The city also gets a new constituency - Nottingham West.

They'll all be part of the new constituency names to get used in time for the next general election.

North East of England, political editor Richard Moss

The North East will lose three seats, Cumbria will lose one.

But no seat in our region is left untouched, with some undergoing huge transformations.

One of the most eye-catching changes could see Tony Blair's old solid labour Sedgefield seat transformed into a winnable Conservative target.

But there are some other decisions which will make life uncomfortable for sitting MPs.

Some communities may also become a little confused as they suddenly find themselves grouped with areas they have little connection with.

Northumberland effectively loses one of its four seats, with changes to those that remain.

In Tyneside, nine seats become eight, with some huge changes to the seats. Three MPs in Jarrow and Gateshead will be competing for two new seats.

Three seats would be retained on Wearside with some boundary changes.

There are currently seven seats in County Durham and Darlington, and those would be kept but, to do so, some parts of Teesside and Northumberland will come into its constituencies.

On Teesside, with Stockton South carved up, Stockton effectively loses a seat. All the seats again face changes though.

And in Cumbria, six seats become five. The biggest loser is Lib Dem President Tim Farron - The Westmorland and Lonsdale seat he has worked so well is carved in three. With Kendal combining with Penrith in one seat, there's the prospect of Farron having to take on rising Conservative star Rory Stewart to survive.

Effectively, Labour are the biggest losers in the region, and I think the Conservatives may be the happiest.

It certainly creates some tighter contests, but also some very large seats geographically.

North West of England, political editor Arif Ansari

The Boundary Commission's focus on equalising the size of constituencies, rather than maintaining historic links, is what's led it to propose some very unusual constituencies.

The North West will have 66 seats, compared with 72 at present; it's more if you include all of Cumbria. Only seven are totally untouched.

Across the region there is wholesale change as seats are renamed and redrawn. MPs are calculating the political ramifications, indeed whether their seats remain at all.

There's been speculation about Chancellor George Osborne, whose Tatton constituency in Cheshire is disappearing. But most of it will be preserved as Northwich.

The real casualty is his Tory neighbour, Graham Evans, who finds his seat of Weaver Vale is dismembered. Part of it becomes Mersey Banks, a proposed constituency of two parts divided by the River Mersey.

Two "cross-county" seats are being proposed for Greater Manchester, one incorporating part of Lancashire, the other including part of Cheshire.

Salford will be totally broken-up with part of the city represented by neighbouring Manchester Central. In Cumbria, there could be a high-profile fight for control of Kendal and Penrith between Lib Dem MP Tim Farron and Tory MP Rory Stewart.

The new constituency jigsaw might be fairer but voters may find their political identity is loosened.

Yorkshire, political editor Len Tingle

Six of Yorkshire's most high-profile MPs will find themselves looking for new seats under the proposals.

Former Labour cabinet members David Blunkett and Hilary Benn will see their constituencies disappear altogether.

The seats of veteran Conservative former frontbencher David Davis and current shadow cabinet members Ed Balls and Yvette Cooper will be split in half.

The Shipley constituency of outspoken Conservative backbencher Philip Davies will also be abolished.

Just five of the 54 seats across the Yorkshire and the Humber region remain untouched under the proposals which will reduce the total number of seats to 50.

David Blunkett says he is "bitterly opposed" to the plan which will see his Sheffield Brightside Hillsborough seat divided between three new constituencies in the city.

Mr Benn's Leeds Central constituency will be split into four parts which will be merged with four other seats

For Mr Balls, the shadow chancellor, it could be the second time he will have had to look for a new seat before a general election.

His previous West Yorkshire seat, Normanton, was abolished before the last election and he had to be selected for the newly-formed Morley and Outwood which he narrowly won.

Conservative heavyweight David Davis would be fighting for selection with his neighbouring Tory MP Andrew Percy as it is proposed to merge both their constituencies into a new Goole and Cottingham seat.

The biggest boundary changes in Yorkshire are in the urban areas of Leeds, Bradford and Sheffield where populations have changed over the past few decades.

Many seats will have relatively minor changes but will technically be abolished and then renamed.

Deputy Prime Minister Nick Clegg, MP for Sheffield Hallam, and Foreign Secretary William Hague's Richmond constituencies fall into that category as they will retain both 80% of their current areas.

Labour leader Ed Miliband's Doncaster North seat is one of the five untouched constituencies.

Northern Ireland, political editor Mark Devenport

The proposed boundary changes will see Northern Ireland's number of parliamentary constituencies reduced from 18 to 16.

The most eye-catching loss will be South Belfast which will be divided between the expanded West and East seats in the city.

Outside Belfast, another constituency going is West Tyrone.

It will be reorganised along with East Londonderry and Mid Ulster into two new seats, called Glenshane and Mid Tyrone.

If the changes are adopted, the losers look likely to be the nationalist SDLP's Alasdair McDonnell, who holds South Belfast and the Democratic Unionist Gregory Campbell, who represents East Londonderry.

Other changes see the Ards Peninsula move from the Strangford Peninsula to North Down and much of Ballymena move from North Antrim to a new Mid Antrim seat.

The southern half of Northern Ireland remains largely untouched by the proposed changes.

The review is also likely to apply to the Stormont Assembly, cutting the number of MLAs (Members of the Legislative Assembly) from 108 to 96.

However, some parties are in favour of a further reduction with just five MLAs representing each constituency, meaning a further cut to 80 assembly members following the next election.