Which is the most important clock in the world? Many visitors to London would answer ‘Big Ben,’ even though this is officially the name of the bell behind it rather than the clock itself. However, as a London blue badge guide, I would say that the world’s most important timepiece is the John Harrison H4 which can be seen in the Greenwich Royal Observatory museum near where the Prime Meridian is marked on the ground.

ZSL London Zoo has petitioned to build nine wooden cabins next to the lion enclosure which will allow visitors to stay overnight – and fall asleep to the sound of roaring.