As soon as leaves appear, their dependent species are quick to follow. This leaf miner is Phytomyza ranunculi which mines Ranunculus species, such as Buttercups and Celandine, as the specific name would suggest.
This close-up of another leaf shows at least three larvae mining the leaves. Larvae shown are about 2mm long.
Germander Speedwell has started to flower. This area will be blue with them shortly. This flower changes colour once it has been fertilised and becomes more violet. I wonder if this is some kind of signal to bees that it doesn't need their services.
I spotted what looked like a gall on the leaves of Cow Parsley:
When I flipped it over to check the underside I saw characteristic signs of a fungal rust. This is Puccinia chaerophylli. Fungal rusts have a tendency to twist, expand and contort leaves and stems in order to increase the available sporing area.