One of the very few patches of the Lake District which Alfred Wainwright never trod was reached at the weekend during the launch of a new book on the famous writer.

Defying rain and mist, a party of enthusiasts held a champagne picnic on Helm Crag, above Grasmere, whose spiky, sheer rock summit was too much for the famously cautious author.

London architect Owen Watson, 22, was cheered by Wainwright fans as he climbed the short but challenging pitch of the Howitzer, the slanting pinnacle which crowns the fell.

Its tiny platform over an abyss was only ever seen by Wainwright from 30ft below. He deliberately left a space in book three of his Pictorial Guide to the Lakeland Fells, saying: "this corner was reserved for an announcement that the author had succeeded in surmounting the highest point. Up to the time of going to press, however, such an announcement cannot be made."

Wainwright's characteristic drawing of the rock also shows himself, frustrated, at the foot of the pinnacle - where he remained on the many occasions he climbed the fell. Widely known as the Lion and the Lamb, Helm Crag was one of his favourite mountains.

He compared it in The Central Fells to a shaggy terrier among sleek foxhounds' - the same description he gives to Haystacks, the Lakeland peak he loved best, where his ashes were scattered.

Owen Watson's climb ended with him waving a copy of the new book, Wainwright - the Man who Loved the Lakes - which goes with the BBC TV series Wainwright Walks. He said: "It pretty nasty - not many holds and very greasy,wet and slippery rock. But I was determined to get to the top and take a bit of Wainwright with me."

The launch party included John Pulford, president of the Wainwright Society, Denis MacShane, the Labour MP for Rotherham and former Europe minister, novelist Joan Smith and some 30 other enthusiasts.

Story and photographs contributed by Martin Wainwright