the 06z from the gfs shows that the Bartlett high continues to re invigorate itself in cycles. In essence this is driving very mild air up from the tropical atlantic - slamming right into the UK, and incursions from the north or brief and simply dilute the mild air to around normal for short periods - before the bartlett reforms once more.
Unfortunately (although many many on this board would like you to think otherwise) this pattern is a rigid one and is unlikely to shift for many many weeks - we are now into week 5 of this pattern - with i believe a similar period still to come. There is nothing on any models at present in in FI suggesting a change to this, so I really wish some posters would stop speculating on otherwise.
I will continue to post my thoughts based on accurate and reliable model watching over many years