Originally Posted by
tommyduk
SB means Ilkeston special production under Gerald O'Donovan. Mine (check the ergo thread) is 2822 and was built in '78. The special ops factory opened in '74, so yours should be '74 or '75.
Congrats on a fab find!
I have SB1092, and was under the impression that mine was made in '77. I concur with your assessment of when the OP's was made, but I suspect yours might have been built a year or two later than think.