Caterpillar - ID help please

 Caterpillar - ID help please

Observation - Caterpillar - ID help please. Description: Pale ochre caterpillar with darker brown side & spine stripes, about three quarters of an inch long. Spotted in grassland near the River Thames at Wallingford. I initially thought perhaps a Marbled White but doesn't look quite right.

Pale ochre caterpillar with darker brown side & spine stripes, about three quarters of an inch long. Spotted in grassland near the River Thames at Wallingford. I initially thought perhaps a Marbled White but doesn't look quite right.