DEVOLUTION could fracture the United Kingdom unless some sort of constitutional ''glue'' is found to keep it together, disgraced Cabinet Minister Peter Mandelson warned yesterday.

The former Trade Secretary urged the Government to use reform of the House of Lords to see off possible tensions between Scotland and England once the Holyrood Parliament is up and running.

Mr Mandelson, who resigned before Christmas following the revelation of his #373,000 home loan deal, is the first senior Labour figure to concede that Home Rule for Scotland could have unforeseen consequences for the Union.

His admission was pounced on by former Tory Prime Minister John Major, who described it as the biggest recantation ''since Satan denounced sin''.

Making his first speech in the Commons since he was forced out of office, Mr Mandelson said reform of the Lords should be used to address the knock-on effects of devolution.

He said: ''Some glue is needed in the UK to set against the possibly fissiparous effects of devolution. I think a second chamber could, if it's constituted in the right way, help contribute some of that much needed glue to keep that United Kingdom together.''

His remarks will delight Labour back benchers who have been warning the Government for months to address growing tensions south of the Border over England's future once Scotland, Wales, and Northern Ireland received their devolved assemblies.

English Ministers and MPs are determined to extract compensation once the May elections are out of the way, and plan to target what they consider is Scotland's over-representation at Westminster and in the Government, and its disproportionate share of public expenditure.

MPs voted overwhelmingly to strip hereditary peers of their centuries-old right to sit and vote in the House of Lords.

At the close of the impassioned two-day debate, an Opposition bid to block the second reading of the House of Lords Bill was defeated by 383 votes to 137, Government majority 246.

Mr Mandelson welcomed the suggestion in the Government's White Paper on Lords reform that the new-look chamber could incorporate representatives of the devolved assemblies as a way of ''bringing together'' the various strands of constitutional change launched by Tony Blair.

However, Mr Major, who fought the 1997 election campaign warning devolution would destroy the Union, expressed astonishment at Mr Mandelson's suggestion that Home Rule might have unwanted side-effects.

''Not since Satan denounced sin have I heard such recantation,'' he said.

Mr Major said he had no intention of defending the hereditary principle, which he described as ''dead''.

But he warned the Government had failed to think through the consequences of Lords reform, which he said would have an effect on the efficient working of Parliament.

''If there had been some way of weighing the implications of the Scotland Bill you might not have had the Scotland Bill and Peter Mandelson would not be worried now about the glue of the Union,'' he said.

The Scotland Bill, he added, ''will prove to be a shambles with a constitutional price to be paid in the future.''

Former Conservative Prime Minister Sir Edward Heath said the time has come for the end of hereditary peers in politics.

Sir Edward told MPs: ''I believe the time has come for the end of hereditary peers in politics. I believe that with absolute conviction. We have now moved to the stage, about to go into the next millennium, and it is time it came to an end.''

He said he did not ''under-value'' what had been done in the past but added: ''We now move on to a purely democratic arrangement.''

The former Prime Minister accused the Government of not having any plans for future developments in the upper chamber. He said: ''I am absolutely astonished that their party could have been in Opposition for 18 years and not have worked out in detail what they want to do about the Upper House.''

To laughter, he said: ''There is a moral there for my own party. You may not get 18 years but what you do get, use it.''

Sir Edward also criticised the deal struck by the Government to keep 91 peers in the Lords as ''impolite blackmail'' aimed at ensuring the Bill got through the Upper House without any trouble.

He added: ''I wouldn't worry about keeping 91 there. I don't believe it will mean very much for them and they may be disappointed in the end - then there will be a lot more bad feeling.''

Mr Mandelson also revealed that he was a force behind the setting up of a Royal Commission by the Government to look at the future of the House of Lords.

He said he had been ''a lonely voice'' in favour of setting up a Royal Commission during Cabinet discussions on how to proceed with reform of the Upper House.

Ministers decided last year to set up a Royal Commission after protests from the Opposition that hereditaries were being thrown out without any idea of what was to follow.