Why are my peas not growing?

Hi I planted peas back in March or April as I normally do but they only grew to like 3 inches tall. Usually they go absolutely mad and I end up having too many peas. I then planted another 2 lots but again they haven't really grown. I grow peas most years in my veggie patch (3X2 metre patch) and they do great. I dug up my whole veggie patch adding two big bags of compost so the soil is good. They seem healthy otherwise no pests or diseases. It has been a bit colder than usual this year in devon but they normally do okay.
Any ideas?

 

@Wardy
I don't have an answer, but I have had a similar issue. I started off some Early Onward in the greenhouse. They germinated and got to about 3-6 inches tall and I planted them out these are doing well after a slow start.
However towards the end of April I sowed some Alderman (main crop), again in the greenhouse, these were planted out after hardening off at the end of May. Even then I wasn't happy with them as the leaves had not opened properly still looking folded. These have just sat and looked at me and yesterday I decided I would take the remaining ones out (pigeons and slugs have had most).
I was thinking that it was the weather or possibly related to the seed being a couple of years old.

 

Thanks it probably is the weather then as I had bought a fresh packet of seeds this year.

 

I'm almost sure this is down to the horrible weather.
Other (unlikely) possible reasons maybe, root/crown rot. Improve soil drainage by adding mature compost to planting bed, destroy infected plants. rotate crops.