Hi Adam,
Pleased you said that as I've been trying to make out Sam's signature in it for the last four months and was going to put his name in the title, but lost confidence... it could well be, I thought 1981 might be a bit late for this style..??
The 1st name could start with an "S" and end in an "l" the rest is a fairly abstact scrawl, but given the surface it's writen on that's not too surprising.
Looking at the signature on the sculpture currently on ebay and your suggestion I feel a little more confident that it might be.