paint on exterior of windows cracking and peeling 4 months after repainting?

[microserf]

any thoughts on why this could be happening? all our edwardian sashes were stripped and repainted in July, and now the paint is all peeling off? got the original painters coming back to "fix" it, but why would this happen in the first place?

What brand of paint did you use?

Sometimes Edwardian windows are oak, which needs a more porous paint. Having said that, our sills are also cracking, despite changing paint. I blame the fact that they are in full sun all day.

I would ask the decorators what primer undercoat they used? did they use the same brand as the top coat, it is always best to use the same brand for both as you then know they are compatible (also what was it oil or water?) How were the windows stripped? did any of the stripping agent get left on? it could be pushing off the top coat.
When were they decorated? was it wet at the time or dry? moisture trapped between coats can cause peeling. Also how many coats of paint did they do? should have been 1 or 2 undercoats/primer (or primer first then undercoat if it was not a dual product) and 2 or 3 top coats and they should have left the correct time between re painting coats (this can be quite a long time if oil was used.)
What way does your windows face? as Greyvix says paint-work in full sun does suffer especially dark colours, not recommended for south facing.
It usually happens due to one of the above, but 3 months is very soon for paint to be peeling off, it must not have 'stuck properly' or moisture is trapped in some way between or underneath the paint.
Whatever your decorator says it is not normally a problem with the actual paint, but a problem with the wrong paint being used or applied incorrectly or something else reacting with the paint.
I work in a shop that sells several paint brands and if we have a suspected problem with paint it gets sent back to the manufacture for testing and 9 times out of 10 it is not the paint, but something to do with the way the paint has been applied or what the surface that the paint has been applied to not being prepared correctly.
One good thing is that the peeling has happened really quickly, so you know that the decorator has to take responsibility for it in some way.
Good luck

Just wanted to say thanks for the advice - they're turning up this week to see what's happened, so i really appreciate people taking the time to reply.