Sweeping changes to parliamentary constituencies across the UK are being proposed, which would see the number of MPs trimmed from 650 to 600.

The Conservatives say the changes would reduce the cost of parliament and even up the number of voters within each constituency, resulting in a fairer battleground.

But critics within the Labour Party , who political forecasters say would be worst affected since they hold more seats with fewer voters, say the changes under discussion have been drawn up to suit the Tories.

Labour also says the figures used by the Boundary Commission for England to produce its proposals were out of date, as they did not include nearly two million extra voters who registered ahead of June's EU referendum.

Within London, the number of MPs would be slashed from 73 to 68 under the proposals, with only four constituencies remaining untouched and many being scrapped or radically altered.

We have taken a look at the six most marginal constituencies in west London to see how how the political landscape there could be altered.

BRENTFORD AND ISLEWORTH

Ruth Cadbury is the MP for Brentford and Isleworth

General election 2015: Labour won with a majority of 465 over the Conservatives

Proposed changes: A new constituency of Brentford and Chiswick would be formed, with the wards of Hounslow Heath, Hounslow South and Hounslow Central going and those of Northfield and Southfield being added

Biggest winner: Conservatives

Why: The three wards being lost are all Labour strongholds, based on the 2014 local election results, while Northfield was won by the Conservatives two years ago and Southfield by the Liberal Democrats ahead of the Tories

What does the incumbent MP think: Ruth Cadbury said: "These proposals are undemocratic boundary-fixing by a Tory government determined to secure a permanent majority in the House of Commons.

"They want to cut the number of MPs but are happy to stuff the House of Lords with their unelected friends. What's more, Hounslow will no longer have two MPs whose seats fit neatly with the borough boundaries."

"When these proposals return to parliament, we will oppose this gerrymandering - cutting the number of elected MPs whilst increasing the number of unelected peers."

What does the Conservative opposition think: Julian Tanner, chairman of the Brentford & Isleworth Conservative Association, said: "I think this gives a constituency which is more blue in tone than red.

"Having said that, we don't take anything for granted. We still have to do the hard work.

"We need to ensure consituencies are of similar sizes, and this review was long overdue. I think we're up to 90,000 voters in Brentford and Isleworth, which is a ludicrous number.

"Brentford and Isleworth is an extremely long and thin constituency, with very different issues at one end to the other. I think there's more logic to the new boundaries."

Interestingly, he added that ex-chancellor George Osbourne, whose Tatton seat in Cheshire would be abolished, may be tempted to stand in the new constituency of Brentford and Chiswick as he lives not far away in Notting Hill.

EALING CENTRAL AND ACTON

Rupa Huq is the MP for Ealing Central and Acton

General election 2015: Labour won with a majority of 274 over the Conservatives

Proposed changes: A new constituency of Ealing Central and Acton would be created, with the wards of Southfield and Walpole removed and those of Askew, Wormholt and White City, and Shepherd's Bush Green added

Biggest winner: Labour

Why: In the 2014 local elections, Labour was third behind the Liberal Democrats and Conservatives in Southfield. Although it won Walpole, which would also be cut from the constituency, it triumphed in all three of the wards due to be added

What does the incumbent MP think: getwestlondon has contacted Rupa Huq

HAMPSTEAD AND KILBURN

Tulip Siddiq, MP for Hampstead and Kilburn

General election 2015: Labour won with a majority of 1,138 over the Conservatives

Proposed changes: A new constituency of Hampstead and Golders Green would be formed. Highgate, Childs Hill and Garden Suburb would be added, with Brondesbury Park and Queens Park removed

Biggest winner: Conservatives

Why: Labour scored a big win at the 2014 local elections in Queens Park, which is being lost, while two of the three wards being added were won by the Conservatives two years ago

What does the incumbent MP think: Tulip Siddiq said: "The Tory boundary review is naked gerrymandering.

"The arbitrary reduction of 50 elected MPs under the guise of 'reducing the cost of politics', while the Conservatives pack the House of Lords with donors and political advisors, severely compromises the integrity of our democratic process.

"It is expected that the proposals will go through several iterations. However, my entire focus is on helping the residents of Hampstead and Kilburn to overcome the many challenges facing our local area."

HARROW WEST

Harrow West Labour MP Gareth Thomas is training for the triathlon through which he's raising money for charity.
Harrow West MP Gareth Thomas

General election 2015: Labour won with a majority of 2,208 over the Conservatives

Proposed changes: A new constituency of Harrow and Stanmore would be formed, with Canons, Harrow Weald, Hatch End, Stanmore Park, and Wealdstone added to the current list of wards and Harrow on the Hill, Rayners Lane, Roxbourne, and Roxeth all removed

Biggest winner: Conservatives

Why: Two of the four wards being lost were Labour strongholds at the last local elections, and four of the five being added were won by the Conservatives in 2014

What does the incumbent MP think: Gareth Thomas said: "Harrow goes from having two full time MPs to only one, while the rest of the borough is carved up to make up the numbers for seats in Brent and Hillingdon .

"These changes will just make it easier for the government to keep funding levels for healthcare, schools, the police and council services in Harrow lower than the rest of London.

"On top of this, these boundary proposals exclude 2 million people who have registered in the last year. This undermines the fairness in our democracy and leaves millions without a fair say in choosing their MP."

TWICKENHAM

Twickenham MP Dr Tania Mathias

General election 2015: The Conservatives won with a majority of 2,017 over the Liberal Democrats

Proposed changes: None. This is one of just four constituencies which would remain unchanged under the proposals

Biggest winner: N/A

Why: N/A

What does the incumbent MP think: getwestlondon has contacted Dr Tania Mathias

WESTMINSTER NORTH

Westminster North MP Karen Buck

General election 2015: Labour won with a majority of 1,977 over the Conservatives

Proposed changes: A new constituency of Queen's Park and Regent's Park would be created. Out would go the ward of Lancaster Gate and in would come those of Kilburn and Queens Park

Biggest winner: Labour

Why: In the last local elections, Labour easily won the two wards being added to the constituency, while the Conservatives scored a resounding victory in Lancaster Gate, which is being removed

What does the incumbent MP think: Karen Buck said the proposals were likely to change considerably between the first draft and the final recommendation, based on previous reviews.

However, she said it was "completely outrageous" that two million people who registered to vote between the cut-off point and the EU referendum had been effectively ignored.

She also said that there was a huge discrepancy within London between the actual adult population and the number of people registered to vote, which should be taken into account.

"This is intended to cut the number of MPs while at the same time the number of unelected members of the House of Lords has been soaring," she added.

"It sounds glibly absolutely fine to have greater equality but that's not what it means in practice because of the discrepancy between the adult population and the number of registered voters in many areas.

"Also, by doing this to such a rigid formula it means in many areas natural communities and boundaries have been ignored."

WHY ARE THE CHANGES BEING MADE?

The Boundaries Commission of England, which has drawn up the proposed new boundaries, was asked to ensure that each constituency has between 71,031 and 78,507 - 5% either side of the average number.

At present there is a big variation in the populations of different constituencies across the country.

The Government also wanted to reduce the number of MPs, which it claims will save taxpayers £66m over five years.

HOW WERE THE PROPOSED NEW BOUNDARIES DRAWN UP?

The commission says it mostly used existing political wards to compose the proposed new constituencies, and tried to take account of geographical features like rivers when choosing where to draw the lines.

WHAT HAPPENS NEXT?

These are only the commission's initial proposals, on which members of the public can have their say during a 12-week consultation window closing on December 5.

The commission must make its final recommendations to parliament in September 2018, after which new legislation will be drawn up.

The new boundaries will apply once they have been formally approved, meaning they could be in place for the next general election in 2020.

To see the draft proposals and have your say, visit the Boundary Commission website.