THE Conservatives yesterday had to brace themselves for the likelihood of yet another by-election defeat, after the death of John Blackburn, the MP for Dudley West.

Mr Blackburn, 61, who died early yesterday after leaving the House of Commons, held a majority of only 5,789 over Labour at the last general election.

He collapsed at the gates in Parliament Square at 11.53pm on Tuesday. Police guarding the entrance called for an ambulance, which arrived within eight minutes and reached St Thomas's Hospital in 10 minutes. Accident and emergency staff fought for an hour to save his life, but he died at 1.11am yesterday.

His death reduces the Conservative majority, which stood at 21 just after the general election, to 14. Although not the most marginal of seats, Dudley West is well on the list of those Labour would expect to claim if it is to win the next general election.

Labour reduced Mr Blackburn's majority from more than 10,000 to just under 6,000 at the last election, and a swing of less than 5 per cent would deliver it to Labour this time. At Newbury, Christchurch, and Eastleigh the Conservatives have lost seats to the Liberal Democrats in this Parliament on swings of up to 35 per cent.

The West Midlands seat is poor territory for the Liberal Democrats, who took just over 10 per cent of the vote last time, Dudley West being one of the Conservatives' most impressive gains at the 1979 general election.

It continued to swing to the Conservatives until 1992 and provides an ideal testing ground for the appeal of Tony Blair's 'new Labour' to the middle class, which makes up a significant part of the constituency on its Staffordshire border.

Mr Blackburn, a former police sergeant and sales manager with an international engineering company, suffered two serious heart attacks in the mid-1980s and had been ill for some time.

Jeremy Hanley, the Conservative Party chairman, described him as 'a tireless ambassador for Dudley' who would be much missed.