Whilst tracking down a mild hot start problem I removed the screw on the bottom of the accumulator to see if it leaked any fuel (unfortunately it did). When putting the screw back in I found it wouldn't seal correctly then threaded. Time for a new accumulator
Had a search and found carparts4less have them for £130 but do £15 off a £100 spend plus topcashback offer 10% so works out at just over £100. Not the most exciting of purchases and a little unplanned but hopefully this will benefit someone else!
Thanks