Watchful eyes for swifts

At this time of year I am on the lookout for the first swifts to arrive from Africa. Usually I see them here in mid-May although I have seen them elsewhere as early as April 27th. 

I am ever hopeful I'll see one in East Anglia, UK in April. My son just has!

UPDATE 0915z:  Whilst walking with my wife to the hairdressers I was observing the sky for about an hour. Sadly, no swifts seen.