Bristol West MP Stephen Williams has been cautious with his expenses claims and boasts one of the lowest allowances bills of all the MPs in the Bristol area.

The Liberal Democrat wrote to his constituents to explain his claims in detail and told them the £24,000 available to MPs to cover the costs of their second homes "was a budget, not a target".

Mr Williams claimed £113,947 in 2005-06, ranking him 517 of 645 MPs, £137,109 the following year, ranking him 337, and £145,585 in 2007-08, ranking him 343.

He played a key role in pressurising Commons Speaker Michael Martin to resign over the expenses scandal.

The Liberal Democrats' universities spokesman was one of the 15 MPs who tabled a motion of no confidence in Mr Martin, who has now been replaced by John Bercow.

The MP did attract media attention over his rent claims on his second home – because the payments are made to a Liberal Democrat peer.

He pays his £1,550 a month rent to Baroness Tonge, who owns the Westminster flat a 15-minute walk from the House of Commons. Mr Williams, who has done nothing wrong by renting a property from Lady Tonge, insists he had never met her before signing up to rent her flat.

Mr Williams was a tax and business consultant for 17 years before he was elected in 2005, and gave evidence about allowances to the Commons estimates committee.

Mr Williams has lived in the same furnished, one-bedroom rented flat in London, which costs £1,550 a month, since being elected in 2005.

He has spent about £900 buying goods for it including a £499 television, £150 vacuum cleaner and a £69 Marks & Spencer radio.

The rest of the cash went on a £35 microwave, £20 toaster and a £22 saucepan, bathroom accessories costing £20 and £53 worth of kitchen utensils.

A typical claim included rent, phone costs of about £12 and food which, under the old rules, could run up to £400 without any receipts being needed. He claimed £20 a day for each day he was in Parliament.

Mr Williams believes the censorship of the expenses document has raised his constituents' suspicions – even though he has nothing to hide.

He said: "I objected to the expenses being redacted. There was no need for it apart from the obvious things like bank details and staff private salaries being blocked. "It should have been completely open and now the redacted documents are causing more of a problem.

"I've had some hostile comments from my constituents saying 'why are the details being obscured?' I had one saying 'why have you claimed for an extension lead?' but they didn't realise it was for my London office. It's not as if it was an extension lead for a DVD player at home.

"The black marks on the expenses give people grounds for suspicion."

Mr Williams rents an office in Fenton Road, Bishopston, and employs a personal assistant who helps the him deal with the huge amount of correspondence he receives as the "second most written-to MP in the country".

He also employs two caseworkers, one full-time and the other part-time, and a part-time publicity officer in Bristol as well as a researcher and two interns at his office in Westminster.

Mr Williams says he normally spends his weekend and part of the week in Bristol and the rest of his time in Westminster, travelling by train.

Among his more notable claims are a series totalling £372.70 for water and the rental of a water cooler from Eden Springs UK in 2005-06.

The MP says he cancelled the contract with Eden when he realised the cost of the having the water delivered, and says he and his staff now fill up an empty plastic bottle with tap water instead.

Mr Williams says he also improved his environmental credentials by switching to green energy provider Good Energy from SWEB, a move he acknowledged would be more expensive for the tax payer, and buying Fairtrade coffee rather than standard coffee for his staff.

The MP also made a number of claims for taxi journeys from his home in Kingsdown to Bristol Temple Meads, at £7.50 each.

But Mr Williams said taxi journeys only made up a third of these trips and he often used public transport to reach the station.

He said: "I have to carry a suitcase and a laptop and sometimes the decision depends on the weather.

"There is no direct bus service from Kingsdown to the station but if it's sunny I can walk to Redland Station and I occasionally do catch the Severn Beach train. If I'm at the Council House I can get the bus, but otherwise I will take the train.

"On the way home I can be more flexible and I can catch a bus or a member of staff will pick me up."