The Mayor of London, Boris Johnson, officially opened Travelodge's 400th hotel at Waterloo and also joined in the party to celebrate the chain's 25th anniversary.

The 279-room Waterloo hotel is the 34^th Travelodge property in the capital and it is planning to open 18 more within the next two years, making it the biggest hotel brand in London by the time of the 2012 Olympic Games.

Travelodge chief executive Guy Parsons said the chain planned to add a further 40,000 rooms across the UK by 2020.

"We will not be resting on our laurels and our target is to double our hotel size in the next decade and to have 1,000 hotels and 70,000 rooms," he said.

To mark the opening of the Waterloo hotel, Travelodge is trialling a free bike hire service allowing customers to see the sights of the capital on a 'Go Cycle', which claims to be the world's lightest electric bike.

By Linsey McNeill