Most likely Ssp. verna based on the thinner petals.
Ficaria verna NS7143 30Apr2016 MJP

Ficaria verna 28Mar2016 NS7951 MP
Most likely Ssp. fertilis based on rounder, wider petals.
Ficaria verna NS7143 30Apr2016 MJP

Ficaria verna NS6058 12April2019 PW

Showing the tubers in the leaf axils of ssp. verna.
Ficaria verna ssp verna NS6373 20Apr2019 PW

Ssp. fertilis showing the fertile achenes.
from Cumbria Botany

Ssp. verna showing few fertile achenes.
from Cumbria Botany

Ssp. verna showing few fertile achenes and tubers in the leaf axils.
from Cumbria Botany