Found by Michael Kilner at Barr Wood Farm, Twechar, North Lanarkshire. This is situated near to the Gartshore Brickworks. Michael has found 3 similar bricks around this location.
B & SS possibly stands for Bairds & Scottish Steel’ viz – William Baird and Co Ltd owned the Gartshore Brickworks. In around 1938, the company underwent reorganisation and entered voluntary liquidation. William Baird & Co Ltd was reconstituted, and the company’s Lanarkshire interests were merged with the Scottish Iron & Steel Company Ltd, of Glasgow, to form Bairds & Scottish Steel Ltd, pig iron and steel manufacturers … Bairds & Scottish Steel – B & SS?
(Note – SBH – I am fairly happy that this is a Bairds and Scottish Steel stamp but I have left the original musings above in case it turns out to be otherwise).
Note the upside-down ‘&’ and possibly the ‘S’s.
Below – A similar stamp from the Gartshore Works.