Confidence: It might be this.
Notes: Resting posture was tightly folded like Scarce Footman but the general impression was of too pale a moth for this species. Yellow edging to the wings very narrow and weak. Hindwing seems very pale, although I still detect a hint of straw-yellow to it which might suggest Scarce.
On balance therefore I think it is this species, but it is not one I have seen before.