A power cut at Alexandra Palace which delayed the Mayoral election count was caused by a “safety systems test”.

The 16 minute power cut - which started at 7.52am - meant the start of the count was delayed by about two hours because the electronic counting system had to be rebooted, but officials are now hopeful they will be able to announce the results on time.

A spokesman said: “During the down time the contingency plan was brought into action and ballot papers, which would normally be done at a later point of the schedule were organised which means the result should be delivered on time as planned.

“We have all worked together to ensure minimum impact to the schedule due to the brief interruption earlier this morning. The cause of the power cut is being investigated.”

Votes from Haringey, Camden, Islington and Brent among others are all being counted at the historic venue.