I honestly don't know as it was Nick at Austins who discovered it. It is the only Mk1 that he has come across with the loom in. It has a very odd history and a lot of predevelopment bits were on it, while officially it wasn't a development car it had for the first year or so been looked after by the press office garage so I think certain things were done...
I would say that the chances of you having the loom are slim with Nick only ever coming across it so far on mine, he has seen a lot of Mk1 260s. Best asking Nick!