From time immemorial travellers have sat on a grass bank and taken bread and cheese from their pack and had these, with water or beer, from a bottle. When the greater part of the population moved around the country on foot or horseback, stopping for refreshment was part of the picture. No doubt many of the Canterbury Tales were told at such a time.
Stopping for refreshment is thus clearly a purpose reasonably incidental to the use of a way and therefore not illegal. But the practice will cease to be legal if the way is obstructed. Where the way is of a width that includes a verge, to sit on a verge and have a packed lunch will cause no obstruction (or, to the extent that the verge is obstructed, since the walked line is open, the obstruction is too small to be likely to found a successful action for trespass to the highway-the matter being merely de minimis).
Of course, if walkers leave the line of a right of way they commit trespass. So if walkers leave the path and move up the hillside for a better view, they are not within the law.
See also
Picnics on Footpaths
