Being in power is a new experience for most Liberal Democrats – but it is proving toxic to their Midland supporters, if party membership figures are anything to go by.

Accounts produced by local parties show that membership has plummeted by nearly a quarter in some constituencies. And Conservatives have also suffered a dramatic decline in membership in parts of the country.

The number of activists deserting the coalition parties is revealed in accounts produced by the parties themselves and published by the Electoral Commission. They show membership levels at the end of 2011, after 18 months in power, compared to those at the end of 2010.

Not every local party sent full copies of their accounts to the Electoral Commission, which means they give only a partial account of the picture across the country.

But figures for Solihull and Meriden Liberal Democrats show that membership was down to 188 at the end of 2011 – from 246 at the end of 2010. That’s a fall of 24 per cent, nearly a quarter.

The accounts state that “the main activity of the local party has been to support Lorely Burt MP and the local councillors with increasing work in all aspects of constituency work and electioneering, and to support our solitary MEP Liz Lynne to hold her seat in the European Parliament.”

Ms Burt is the MP for Solihull, elected in a surprise win over the Tory incumbent in 2005.

Other Lib Dem seats have also seen a decline in membership, but not always so dramatically. In Westmorland and Lonsdale, where the MP is Lib Dem President Tim Farron, membership fell from 454 to 399, down by 12 per cent. Party membership in Yeovil, the seat once held by former party leader Paddy Ashdown, fell from 483 to 400, down by 17 per cent.

Ms Burt said: “We had a big spike in membership during the general election campaign and obviously we are disappointed we haven’t managed to keep those additional members.

“But the trend in party membership is always downwards following a general election.”

West Midlands Conservative politicians have experienced a similar exodus of members. In Sutton Coldfield, where the MP is Conservative International Development Secretary Andrew Mitchell, membership was 314, down from 408, a fall of almost a quarter. Meriden, where the MP is Conservative Environment Secretary Caroline Spellman, did not publish membership numbers.

However, the party revealed that membership fees received had fallen from £15,356 in 2010 to £12,104 in 2011. Mid Worcestershire, represented in the Commons by Tory Peter Luff, reported that membership at the end of 2011 was 372, down from 590 in 2010, a fall of 37 per cent. Stratford-upon-Avon, where the MP is Conservative Nadhim Zahawi, reported membership fell from 963 to 852, down by 12 per cent.

Mr Mitchell said: “Membership of constituency associations does tend to decrease in mid term. But interestingly, in the last few weeks we have seen 11 new members join.” No Labour constituency party in the West Midlands submitted membership figures.

While MPs put a brave face on the figures, the effect they can have on the ability of parties to mount effective campaigns has been highlighted by Tory grassroots blog Conservative Home, which reported Boris Johnson’s campaign had to pay for election leaflets to be delivered in parts of London where there is a sitting Conservative MP, because of the weakness of local associations.