According to our very own Retrobike archive, the 91 Orange catalogue shows an Orange 'Formula Orange' - a black hand made MTB frame option - as Michael described.
The Orange 'Formula' is the road bike made from 753 steel in classic Clockwork colourways - I cannot find out the year(s) of build for this frame - the only road frame featured in the archive is the 93/94 raw aluminium 7005 'Dynamo', which I have never seen in the flesh.
I would love to know who made the road frames and how many were made. At the end of the day, you'd wait a long time to see any of the above go by today...!
All (!) the Formulas were MTB, the one road frame is Steve's own road bike made from the same Formula tubing and welded by him.
Dynamo was a 7005 alloy frame, most were anodised grey or purple, some painted ( usually where the anodising wasn't perfect) I'm not certain on this but i think the sizes were 50, 53, 57 and 60 and less than 100 were made. Dynamo has twin seat stays not a mono stay. I have one of these in the garage and will post photos.
D2 replaced Dynamo in about 94, it has the monostay and is still 7005, sizes were 50, 54 and 57 once again less than 100 units. Jonny Clay and Adrian Timmis used D2's when they represented Orange on the road.
There are also 2 Ti Dy's these were titanium road frames, mono stay, similar construction to a T2 MTB. We still have 1, i think Jonny might have the other.