This is a planted tree in our front garden, here when we arrived. We are in N Cumbria around 430ft AMSL.
Around 4m tall, bushy character, multiple twisted and gnarled trunks, not thorny. Leaves not serrated, not lobed, broadly oval with slight point at end, up to 7cm long, slightly yellowy-green, matt and hairy on both sides, and in opposite pairs. Flowers are small, pale yellow, about 1cm in length, two petals, 5 carpels, 1 stamen. They occur in pairs at the end of a flower stalk about 2 cm long, two flower stalks growing from the base of each leaf-pair. The tree is constantly buzzing with bumble and honey bees. Been in flower since mid April.
I can't find this in the Collins Tree Guide, and using the NHM tree key leads either to an Oleaceae (Manna Ash) or a Viburnum. Fairly certain it isn't the former, but the inflorescence doesn't seem to fit for Viburnums either.