A peer has caused a major constitutional clash by ambushing plans for a supreme court to replace the Lord Chancellor.

Lord Lloyd of Berwick, Deputy Lieutenant of East Sussex, won backing for an amendment which blocked the passing of the Government's Constitutional Reform Bill.

Lord Lloyd, a Conservative law lord, sparked Government fury with his amendment, which sends the Bill to a special select committee.

Commons leader Peter Hain has threatened to reintroduce the Bill in the Commons and invoke the Parliament Act to force it through.

As well as scrapping the ancient office of Lord Chancellor, the Bill would eject the law lords from the upper chamber, replacing them with a supreme court as the final court of appeal.

It would also establish a Judicial Appointments Commission.

Lord Lloyd, 74, who lives at Ludlay in Berwick, near Polegate, insisted there were huge concerns which needed investigation by a select committee, including the cost of the new Supreme Court.

The cost of running the House of Lords as a judicial body is £623,000.

The estimated cost of a supreme court could be as high as £8.7 million.

Lord Lloyd said backing the Bill without further investigation would be the equivalent of buying a "pig in a poke".

He told peers: "Great changes in the constitution, especially when they concern the administration of justice, should be made by consensus and not by Government diktat."

The House of Lords backed Lord Lloyd's amendment by 216 votes to 183.

Lord Lloyd said he had not given up hope of saving the historic post of Lord Chancellor, currently held by Lord Falconer.

But he denied he was trying to "wreck" the legislation by forcing it into committee.

Lord Lloyd claimed: "The select committee would need about three months to gather evidence and to form a view.

"It could report by the end of July, which means the Bill could be through this House by the end of October and, as a matter of course, it could and would be carried over in the Commons to the next session."

Baroness Valerie Amos, the leader of the House of Lords, told peers they had taken a "very serious" step.

Eton-educated Lord Lloyd, formerly Sir Anthony Lloyd, was made a life baron in 1993.

He married Jane Helen Violet, the daughter of former High Sheriff Cornelius Shelford, of Chailey Place, Lewes, in 1960.

He was appointed to the Queen's Bench Division in 1978 and made a Deputy Lieutenant of East Sussex in May 1983.

His interests include membership of the Glyndebourne Arts Trust and the Society of Sussex Downsmen, for which he was proposed as president in 1996.

He ran for Cambridge University at White City in 1950.

In Who's Who he lists his hobbies as music and carpentry.

Lady Lloyd became Sussex's first female High Sheriff in 1994, giving her higher legal jurisdiction than her husband.