Henry Bergen, born in New York, was a writer and collector of early wares from St Ives and slipware from Winchcombe pottery, which have since been donated to the Potteries Museum in Stoke-On-Trent. Bergen, Leach, and later Michael Cardew became good friends and Bergen contributed greatly to promote Leach on the London scene from a literary side which came to fruition with the publication of A Potter's Book in 1940.
On his occasional visits at Winchcombe Pottery, he worked with Cardew and provided designs based on slip-resist techniques and impressed lettering as in this example.
For a similar example and further biography of Bergen, see John Edgeller, Slipware and St Ives: The Leach Pottery 1920 - 1937 (Winchcombe, 2010), pp. 21 - 22