Last updated at 17:04 29 October 2005

Big Ben will today be stopped for maintenance work, which will include retuning. The famous clock was stopped from 9am chimes until about 4pm tomorrow.

It is the longest stoppage since 1983. The move is to allow in-house engineers to carry out a thorough planned inspection of the clock in conjunction with specialist testing engineers.

Engineers from the Whitechapel Bell Foundry will also replace the rubber hammer buffers on three of the four quarter bells and the hour bell.

This is routine replacement of parts. The engineers will also need to re-tune the bells, which may take several hours to complete.

The work is part of a comprehensive maintenance review and is intended to form the basis of a new five and 10-yearly maintenance regime to ensure continued reliability into the foreseeable future.

Big Ben fact file: