I'd echo that it's got all the features of Toni's work and that price sounds about right at the moment, too. Yep, Palitoy Toni's (on the ROTJ 65 backs) do around £70 whilst the real deal is now over £100.
This on a Palitoy 45b is easily £250. So this on a GM 45 back, if it was real, I would hazard a guess at being north of £400 with a caveat: it would have to be very clearly not a TT. And that really is a guess: genuine GM 45 backs are pretty hard to find so it's hardly surprising you can't find one to compare it with.