I found this unusual double-flowered cultivar of Midland hawthorn Crataegus laevigata 'plena alba' in a hedgerow in Durham city a few days ago.
Midland hawthorn isn't very common in Durham and this double-flowered version is rarer still - this is the first time I've seen it.
This is common hawthorn Crataegus monogyna, which is the prevalent hawthorn species in hedgerows in the North East. Can't honestly saw that double-flowered hawthorn is an improvement on the wild type.