Measuring a tree the same height as eight double decker buses is no easy task but not one the National Trust has shied away from.

The organisation has declared a Norway Maple at Prior Park Landscape Garden in Bath the national champion tree after being measured at 36 metres (118 feet).

This makes the Maple the tallest in the UK by a clear six metres.

The previous champion tree, growing at Glamis Castle in Angus, Scotland, is 30 metres tall.

Matthew Ward, National Trust head gardener for Bath, said: "For years I've looked at this tree and thought it was unusually big but when we finally measured it ourselves we realised it was one of the tallest in the country."

The tree is in a sheltered part of the park growing among other trees on a bank making the process of confirming its height all the more tricky.

The measuring was done by a team from the Tree Register who climbed the Maple and used a combination of poles and tape measures to find the exact height.

"It hasn't been planted up as a specialist arboretum and because, in the past it had been left alone, there are a lot of self seeded trees creating quite a natural feel to the woodland," Mr Ward said.

"We are in a hollow close to the city and it is a sheltered pleasant spot which the trees certainly seem to like.

"As well as this superb Norway Maple we have a number of yew trees which grow particularly well."

The National Trust is maintaining Prior Park in the spirit of Ralph Allen, the 18th century entrepreneur who created it, as his vision of blending a garden with the natural landscape.

In addition to the work at Prior Park, the Trust is carrying out a three year survey to reveal the full extent and condition of the estimated 500 tree avenues in its care.

The project began last year to help prioritise funding and bring together the stories associated with them.