Photos: BT Tower at 40

London's landmark through the years - in pictures

The BT Tower, one of London's most famous landmarks, was opened by the then Prime Minister Harold Wilson 40 years ago on 8 October 1965.

All photos: VisualMedia

Originally known as the Post Office Tower, it was the UK's highest building at the time, standing 189 metres tall including a 12 metre London Weather Centre radar mast.

The tower was designed to meet the increased demands of broadcasting by allowing the use of microwaves instead of landlines for transmitting television signals.

Today the tower handles around 3,000 switched calls per day, 99 per cent of all live football and terrestrial television passes through it and it is a Grade II listed building.

It cost £2.5m to build and can stand up to 23 centimetres shorter in winter than it is in summer - because of contraction and expansion - and is designed to sway no more than 20 centimetres each way in winds up to 100mph.