TQ9694 : Breaching the Sea Wall
I believe the main reason this was done is to satisfy planning conditions regarding a development further up the coast which devoured a wetland area considered important for birds.
Something of a global-warming bandwagon going on to claim this is due to increased sea levels and storms etc (as in the media widely)
However it's an interesting experiment as there's no doubt these hard defences often cause as many problems as they solve and can never be a satisfactory long term solution.