William is remembered for his breeding of the Duke of York potato, which is still grown though in smaller quantities than in earlier decades.If you cannot find a source of Duke of York I am sure that you will enjoy some its offspring, which are widely available; both Desiree and Cultra were bred from Duke of York.
However, he also bred new varieties of peas, some of which won awards in trials carried out by the Royal Horticultural Society (RHS) each year.
Newspaper articles about the family say the following about William.
“Some of the finest peas now selling in this country were originally produced at Gourdas”.
“He also propagated a new garden pea and an English seedsman bought the whole rights”.
There is no information about which seed company bought William’s new variety. I have found the names of the peas submitted to the RHS but I have not been able to link them to any company.
I do have copies of letters written to Suttons Seeds on behalf of Thomas’ widow shortly after his death in 1912. This correspondence was about new varieties of peas Thomas had produced and asked if Suttons was interested in purchasing the pea seed. It is clear from these letters that Thomas had previously written to Suttons. Could it be that William had also sold his peas to Suttons? The Suttons archive is at Reading, too far for me to carry out the research, but work by a local researcher has so far not found any records.
In 1918 there was an article in the Aberdeen Daily Journal about some of the last potato varieties that William had produced. He had given them to Simon Campbell, head gardener at Fyvie Castle, to grow on. The whole stock had been purchased by Messrs Dixon and Company in Edinburgh. Should this be Dickson since there were seed merchants of that name? So far I have not had any luck in tracing any information about these potatoes or about Dixon/Dickson.