It seems the oak and ash question is more complicated than I thought...
Oaks further up the lane from the ash I photographed last week looked as if they were greening but this was because they were in flower not in leaf.
Across the fields, in a plantation to the west of the village, oak and ash are at more or less the same stage - leaves only beginning to come out.
But in a lane to the north, at the bottom of a dip, the oak and ash that face each other across the carriageway are at completely different stages - the oak well out and the ash only just appearing (more fully in leaf near the top of the tree). See above photos.
In the hope of a summer splash, I'm going with these two!