HMS Ambush latest of Royal Navy's next generation of submarines launched

HMS Ambush, the second of the Royal Navy's new Astute class of nuclear submarines, is powered by a nuclear reactor the size of a dustbin.

It is 97m long, the equivalent of 10 London buses, and weighs 7,400 tonnes compared with the 5,000 tonnes managed by its predecessor, the Trafalgar class.

It has the biggest "ears'' of any sonar system in service today, with the processing power of 2,000 laptops.

The nuclear reactor which drives the propulsion system is roughly the size of a dustbin but will last the 30-year life of the boat without needing to be replaced.

But there are some other big numbers to bear in mind - the first three Astute class submarines (HMS Astute, Ambush and Artful) cost the Government £3.8bn, according to last year's National Audit Office report, compared with an initial contract for £2.58bn.

That report also showed the project was 47 months late, with an original in-service date for Astute of May 2005.