A superb used example of this King George V postage stamp from the so-called Seahorse series.  This is SG403 £1 green, the highest value denomination in the series which was only printed by Waterlow in 1913. Single cypher watermark (W110).  Lovely colouring and all perforations intact. Lightly cancelled albeit the markings are unclear.  A very special stamp.  Please refer to scans for condition.  Stanley Gibbons price this stamp at £1,400 in their 2025 catalogue, representing what they see as the current market RRP.