Yellowing mangetout leaves

Transplanted a 100 or so mangetout plants out into the allotment about 2-3 weeks ago.

They looked grat when transplanted but over the last week have been getting yellower leaves

They are still growing well but just concerned about the yellowing.

Ive been giving them a good water when it looks like they require it

Any ideas?

It sounds like you are overwatering.  Check the moisture (stick your finger in the soil)..if it is still damp then they dont need watering.

I'd also give them a quick feed to boost them, but only one.