Friday 21 June is the longest day of the year, and since time immemorial people of all faiths and none have marked the occasion of the summer solstice by rising to greet the dawn.
London cyclists do this in their own special way by riding through the night from Greenwich to Primrose Hill, following a tradition established by the late Barry Mason.
This year's Midsummer Madness ride will follow a familiar but never entirely predictable pattern, with the early risers setting off from Cutty Sark Gardens in Greenwich at 2am on the morning of the solstice before stoping at Southwark Needle by London Bridge at 2.30am to collect more riders.
2.30am Set off from Cutty Sark Gardens, SE10 9LW
2.30am Collect more riders at Southwark Needle, SE1 2SY
3am Stop for coffee and a chat at Bar Italia in Soho
4.30am Reach the top of Primrose Hill
Following the sunrise some will cycle back across the river for breakfast in a Southwark cafe, before heading for work or home to sleep. Others will hang around Primrose Hill or do their own thing, with all bidding a fond farewell to friends old and new, promising to return next year for more of the same.
The Midsummer Madness cycle ride is brought to you by the Dog & Bell Crew: an informal collective of southeast London-based social cycle ride planners and members of the London Cycling Campaign.
This year's ride leader is science journalist and fixed-wheel cycling evangelist Francis Sedgemore.
There are no rules other than those of the road, good sense and common courtesy.