Alright, I'm stealing this tip and the following information from Jon Vidar Bergan, also known as a walking musical encyclopedia, so thanks, pal! Here we go:
"Blue-eyed soul at its best, and a Northern Soul favourite. "(Accept My) Invitation" from 1966 is the A-side of the fourth and last single by British group A Band Of Angels - fronted by Mike d'Abo before he joined Manfred Mann. He's also the songwriter."