I'm not sure I remember Orbit, but I am a big fan of anything British made and fillet brazed, so I'm looking forward to seeing how you build works out.
They were a bit of a "beardy" handmade touring bike company, and had (have) a good reputation for touring frames, and dipped their toes into MTBs like other road bike builders like Overburys, Bromwich and Donahue etc.
They have moved around a bit, originally Sheffield, this was apparently made in Coventry but now they are in Sheffield again. I think they contracted out some or most of the actual frame building.
Unless they advertised in the mtb comics, then I probably wouldn't have known about them. I have to confess I don't remember Overbury's either, and they are only 25 miles away!
That said, financial constrains meant my sights were set a lot lower than the lofty heights of 'hand made' British frames back then, probably why I have so many now, as I consider them such amazing bargains.
If you are going to get the frame powder coated, may I suggest a couple of RAL codes? Have a look at 1018 or 1026