Y is quite trickly so I will go with James Radley Young (1867-1933), a designer/potter who had studied painting and modelling at the Sheffield School of Art before working at the Poole Pottery, from 1893 until leaving in 1901 but returning after a few years.Where he designed tiles and art pottery, including lustre glazes and decorated "Omega" workshop type items.
He also established the Hammer Pottery at Haslemere in 1901 with WW Stallworthy. Haslemere Ware was produced from 1901 until 1911 with the wares are similar to other local potteries such as the Wrecclesham and Farnham potteries. Incised marks.
For book on Poole Pottery - try