Newly painted bargeboards cracking

[Gazelle1]

We had a painter decorator paint our bargeboards - he sanded, filled and painted with two coats of Dulux Weathershield a month ago during a fairly cool period of weather. It's been quite hot the last couple of days and I've just noticed that the paint seems to be bubbling - difficult to see from the photos but it's not actually flaking off but definitely coming away from the wood. What's the most likely cause and is the painter at fault?

 

[Wayners]

Damp in the wood.

It's a good idea to test the wood for a damp reading before painting.
The wood don't look in good condition from the photos

 

[blup]

A month ago the weather was still cold and damp, so the wood was likely also damp. Did he offer advice on the likelihood of it failing?

 

[Gazelle1]

No he didn't offer any advice on it failing. It had been dry for a while where I am (south east) for most of the month before he did the work but maybe it was still too early in the year.

 

[Gazelle1]

Could it be the paint used? We've had it painted twice before with more 'breathable' paint and not had this problem. This time the decorator used Dulux Weathershield Wood paint which is much thicker and might be preventing the natural expansion and contraction of the wood in the sun.