Looks like Polyanthus denticulata: drumstick primulas - good for massed planting in damp borders or boggy soil. Its common name comes from the dense, round flower-head held on top of a 30cm (1ft) stems, which bloom between March and May. The majority are mauve; exceptions include P. denticulata var. alba, which is pure white, and the bright 'Robinson's Red'.

Thanks for that- it is indeed in boggy soil!