I'm no expert but I reckon it'll be a Redac brick as their works was in Huncoat. Does anyone remember the buckets that used to cross over Burnley Road from the quarry to the Redac brick factory?
worked at redac for a short spell in the dinasor age used to stack the unbaked bricks on pallets but cant remember if they had huncoat etc on,but concur with yerself as thats a good bet.
