I will second/third/etc. Dave & Toni Arthur.
Also singing at around the same time as them were :

Geoff & Pennie Harris

Remember them as a duo ? I believe that Geoff Harris is still performing and is back in touch with the Halliard members (who he had also sung with). I heard very recently that Pennie Harris is still living in the Colchester/Essex area, but no longer singing. That's a great pity.

- jeanie