Tough one as there is some intense heat already building in southern Europe but the models are consistent in wanting to start May with a cool NE wind for the UK. 

So going average, cool start very warm finish 11.7c

Thanks GW great effort as always

It feels like the warmth of recent months has "drained away" quite a bit... So let's say 10.8

11.1 for me please. Tempted to go lower given the models but it would go so against the current run of play.

11.6C please.

From the looks of things we'll be in desperate need of a decent warm spell by the time we reach the second-half of May.

To help bring this about, I shall go for an uninspiring 10.7*C which is a whole 1*C below the LTA (1981-2010).

Cheers and here's hoping that does the trick  

EDIT at 9:30 on 1st May:

I didn't expect my trick to work that fast on the GFS model! A westward trend in the positioning of the high-lat blocking and troughs trying to invade from the Atlantic. Stick or twist?! The ECM 00z is not exactly with that but does look very, very strange days 9-10. Trouble is, as May climatologically warms up quite a bit as it goes along, any changes for the middle part of the month could lift the CET outcome dramatically.

I forget what the rules are on late entries (is this even late these days?) but if there is a penalty that is less than (edit at 15:58- 0.7*C not 1), I'd please like to revise my estimate up to an incredibly boring 11.4*C because to be honest I'm just not sure what to trust right now 

11.8c please

11.7C please GW.

10.9°c please.

I'll go for 11.89C

12.2C please

Almost left it too late.

I'll go for

11.5C