It all began with the break of the 1.3000 level and since then, there hasn't been any reprieve for the pound against the dollar in a rather straightforward 400+ pips move.
Technical support after technical support keeps giving way and now we're headed towards a test of the 1.2500 level. That and the 61.8 retracement level @ 1.2495 will provide the next key layer of defense for the pound.
There have been a couple of reasons why the pound is seen struggling and that hasn't really changed. For one, the dollar itself is also firmer this month with plenty of buildup towards the Fed come 4 May. Add to the fact that the BOE is feeling a bit shy all of a sudden when it comes to rate hikes, it doesn't help the pound's case.
Then you have the sentiment play where the pound has performed much like a high beta currency as of late and the more sluggish risk mood in the past few weeks certainly hasn't helped in that regard.
Throw in a key technical break after several attempts of holding at 1.3000, and the floodgates have certainly opened.