I strongly believe that there was no chassis number stamped directly into the chassis. From the recent experience of registering my Peerless in Germany after importing it from England I learned that cars built before 1960 do not need a chassis number stamped in over here - the chassis plate as in our case is sufficient. This saved me from stamping the chassis number in on my own which I had planned. However, if the car is dismantled anyway, I would still recommend to take the chance to stamp the number on in an easily visible place.
I'm sure allan house told/showed me a chassis that had a stamp or perhaps it was a plate fixed to it...I can't remember, will quize him when next we meet.
I have seen several cars with stamped chassis numbers including one on one of my own Warwicks. The chassis numbers I have seen are always on a small 1 inch by .75 inch metal plate which is stamped with a three numbers and tack welded on to the outer of the two chassis rails that go down the (UK) drivers side of the engine (the inlet manifould side). The plate is tacked on approximately 1 inch back from the front cross member. My stamped chassis number makes no sence to me at all as it looks nothing like a GT2... number. As Nigel says, Alan may know more.