UPDATE 1-Britain's ruling party vows to learn from defeat

(Updates throughout)

By Adrian Croft

LONDON, May 3 (Reuters) - Britain's ruling Labour party pledged on Saturday to learn lessons from a crushing defeat in local elections that newspapers said may signal the beginning of the end for Prime Minister Gordon Brown's government.

One Labour legislator said ministers were involved in talks on whether there should be a challenge to Brown's 11-month-old leadership. However, most analysts believe a challenge to Brown so soon after he assumed the leadership is very unlikely.

Labour lost the prestigious post of mayor of London to the opposition Conservatives, capping its worst local election defeat on record.

Brown was preparing to unveil a new legislative programme, possibly as early as next week. The government gave no specific plans of how it would respond, but Brown was due to give television interviews on Sunday.

Columnist Jonathan Freedland, writing in the left-leaning Guardian newspaper, said the Labour government appeared to be "about to enter the twilight" after 11 years in power.

The Conservatives, who lost the last three parliamentary elections, were elated after winning an estimated 44 percent of the vote to Labour's 24 percent.

"We've shown there is an alternative. We must now prove it," Conservative leader David Cameron said.