Guilty, guilty, guilty... the pleas that signalled an MP's disgrace

Now he finds himself on the brink of being kicked out in disgrace, under pressure to resign before he is pushed – and the constituency he has represented since 1987 is bracing for a by-election, albeit hardly a nail-biter given Labour's 11,000-vote cushion.

In Court One of Southwark Crown Court yesterday the former National Union of Mineworkers' official cut a glum figure, speaking only to confirm his name and answer each of the three times with the same "guilty" response.

He had previously denied dishonestly claiming a total of more than 25,000, arguing that lax Commons allowances were designed to "supplement" the income of politicians, but his barrister, William Coker QC, said his client admitted wrongly obtaining a revised sum of about 14,500.

It comes at the end of an investigation launched when, in the throes of the expenses scandal, the Daily Telegraph alleged that over four years Illsley claimed over 10,000 from the House of Commons in expenses for council tax despite being charged only 3,966 by his local authority thanks to a lax system which meant receipts were not required to back up claims.

When police investigated they found further discrepancies on claims for telephone usage, service charges and maintenance, and insurance and repairs at his second home in Renfrew Road, Kennington, south London.

In four weeks he will return for sentencing, but the 18-month jail term handed out to former Labour MP David Chaytor last week over his fraudulent expenses claims sent out a message the courts are ready to be tough.

The events are embarrassing for Labour, which allowed Illsley – the party's NHS spokesman in opposition in the 1980s – to stand at the General Election despite widespread reports that police were investigating his claims.

Concerned party officials had made clear to Illsley, a veteran of several House of Commons select committees, that any post-election action against him would cause problems for the party but he is said to have been adamant the police investigation would come to nothing and without any hard evidence of looming charges party officials felt helpless to stop him standing.

Piers Tempest, the Tory candidate who fought Illsley at the General Election, told the Yorkshire Post last night it was up to Illsley whether to resign but urged a resolution as soon as possible.

"The sooner they're clear on what's going to happen the better, he said. "Places like Barnsley have got to have very strong leadership over the next year or two to get through the recession and into a more economically positive climate.

"That's the one thing people should be focused on. If it's Eric who's going to continue to represent the constituency fine; if he's not there should be a by-election as soon as possible to ensure the residents are fully represented and their corner is being fought."

If Illsley quits or is forced out – either automatically by receiving a 12 month jail sentence or by a resolution from MPs if he is treated more leniently – it will spark the second by-election of this Government, after tomorrow's crunch vote in Oldham East and Saddleworth.

Barring a shock, Labour will keep hold of the seat which Illsley won with a majority of 11,093 in May. For the coalition it will prompt an intriguing battle – the Liberal Democrats won just six more votes than the Conservatives at the General Election.

HOME-TOWN BOY IN A SAFE LABOUR SEAT

ERIC Illsley is Barnsley born and bred, having lived in the town for his entire life apart from his university years in Leeds.

A Grammar School boy, he gained a degree in law before going on to work for the National Union of Mineworkers in 1978.

He was first elected as MP for the safe Labour seat of Barnsley Central in 1987 and has held it ever since, having joined the Labour Party in 1979.

In the 1990s he became a whip for the Labour opposition before becoming spokesman for the NHS, Local Government and then Northern Ireland, but when Tony Blair swept to power in 1997 there was no job for him in Government.

Instead he joined the Foreign Affairs select committee, and later sat on several other select committees, eventually chairing the short-lived Yorkshire and Humber select committee abandoned by the coalition.

Largely loyal despite in many ways being "old school" Labour, he was involved in exposing solicitors who double charged former miners who were claiming compensation.

A keen caravaner, the father-of-two - married to Dawn - has been paid a parliamentary adviser to the Caravan Club.