12.20 - 13.10. West-east pass mid-slope, then up to the earthworks and the long barrow. Little of interest on the plateau at the top, but ABs seen at regular intervals along the entirety of the scarp. Given the sweep and height of this wonderful natural arena, there must be upwards of 500 individuals at this location. For their scarcity value this year I should also mention one male Brimstone seen at New Mill SU183619 and one fresh Small Tortoiseshell at foot of Giant's Grave SU162630 later on in day. 3 ST and 2 PL seen on Knap Hill following day too.