These Ordnance Survey benchmarks, of which there are only 200 in the UK, are the cornerstones of the countrywide height measurement network, the mean sea level reference point being the Newlyn Datum in Cornwall. Unlike the more familiar trig points, they are still in use and are regularly checked. The concrete block is set on bedrock for stability. The height is specified as 124.0106 metres. Such precision! See closeup NZ1494 : Fundamental Benchmark For full details see Link
The premises are no longer Mr Greens the Butcher. His business has been transferred to Longframlington in the next village 4 miles north on the A697. Another business is now in occupation at the Longhorsely premises.