The pale blue one in the pic is a 17, they are about 15 ctc. Never seen a pre 98 one, there are plenty of 17's about though or a Clockwork or Prestige in the smaller sizes.
Having taken a closer look I agree it's a 15 frame, but not a P7, it's a Clockwork.
Down tube is far too narrow in diameter, not oversize like a P7. Also the bottle cage bosses don't have the star shaped surrounds that a P7 has. There's never been a 15 inch P7 featured on here and still doubt they were ever produced.
I'm not trying to be negative, but doubt you will find one, if they exist.
Why not contact Orange direct?