LILAC HIBISCUS : Alyogyne huegelii
Escaped introduced plant.
Compare to cranesbill geranium index.asp?pageid=732585
Hibiscus plants are very varied - from small flowers such as this to shrubs from which hedges can be growb. This one comes from Australia and is only included because it was found growing on the upper Leven towpath and is similar to a native species.
They can be identified from their protruding stigma and stamens.
UK NATURALIST : https://uk.inaturalist.org/photos/156814766