This tree is actually Sequoiadendron giganteum but it continues to be known as Wellingtonia as this was the first name given to it and the name stuck.
Seed was brought to Britain in 1853. In California it grows to almost 100m in height. The largest trees in Britain are little over half that size.
There are quite a lot of Wellingtonia trees up and down the country that were planted in the late 1800s when seedlings became widely available. This tree will be from that period. The bark of the tree is notable. It is tough, fibrous & fire-resistant, allowing the tree to survive a forest fire as long as it is not too intense.