One of those deeply frustrating moments where I know that something is apparently about to happen, but can’t find out anything more than “it is happening”.

It would seem that there will be a flotilla of hot air balloons flying over London very early on Sunday morning.

An air traffic alert that has only just been issued reads:

CROSS-LONDON BALLOON FLIGHT. UP TO 50 HOT AIR BALLOONS WILL LAUNCH FM 513204N 0000507W (SHOREDITCH PARK, E LONDON). OPS CTC, TEL 07753 389365 / 07773 300372. BALLOONS MAY BE FOUND UP TO 15NM DOWNWIND OF LAUNCH SITE. PILOTS ARE REQUESTED TO EXER CTN IN THE VCY. FLT WI CONTROLLED AIRSPACE WILL BE SUBJ APPROVAL FM THE APPROPRIATE ATC UNIT. 15-05-0695/AS 5.

Which in plain English, puts the launch site at the Shoreditch Adventure Park, which isn’t far from Hoxton overground station. Quite which direction they fly off in will be down to the wind direction, and met office predictions suggests the balloons will be heading over East London.

The alert is for the balloons to be in flight between 03:15 GMT (04:15 BST) to 07:00 GMT (08:00 BST) on Sunday morning (7th June).

Other than that, I know nothing else about it — research has been surprisingly fruitless for what seems to be quite a large event.

Update — Appears to be part of the Lord Mayor’s charity – www.balloonsoverlondon.com and does involve a huge fleet of hot air balloons.

But if you fancy it, in theory, lots of hot air balloons, over Shoreditch, early sunrise. Could be awesome.

UPDATE 2 – Photos taken this morning at the take-off