Sea Asters ?

Sea Asters ?

Observation - Sea Asters ?. Description: Saw these growing on a shingle beach in Bracklesham Bay - thought they may be Sea Asters but the head;floret ratio seems wrong and according to reference books Aster tripolium doesn't flower until July Can anyone help with identification?

Saw these growing on a shingle beach in Bracklesham Bay - thought they may be Sea Asters but the head;floret ratio seems wrong and according to reference books Aster tripolium doesn't flower until July
Can anyone help with identification?