From Peachysteves post recently on 8th March…(thanks for the prompt).
I eventually got around to checking for both Cherry Plum and Blackthorn species on Shroggs Road reclaimed landfill site. There is a large flat, and very boggy grassland area, which is very good for lots insects in summer but not a lot visible in winter.

There is one large planted tree area adjacent to Brackenbed Lane and another banking of planted trees alongside Shroggs Road. The trees in both areas were planted around 1989. Our son and pupils of Lee Mount Junior School planted the trees on the banking in liaison, I think, with Calderdale’s Million Trees Initiative.

I found around 6 groups of Blackthorn, Prunus spinosa, all on the grassland side of the tree belt and looked for the green sepals between each petal along with the black twigs and sharp long thorns. the flowers are just starting to emerge on some plants whilst another group was in full flower.

Below
Later in the morning I came across an isolated small tree on the same site, in flower, and carefully checked the twigs and flowers. I came to the conclusion this is probably the Cherry Plum – Prunus cerasifera
The flowers looked marginally larger than the Blackthorn. They were on green twigs and the sepals were curled back. Click on the images to enlarge.