Originally Posted by Kate @ OTN

Hi Paddy,
Sounds to me like it may just be wear and tear from the weather.
I wouldn't worry for this season - a lot of plants are starting to look drab and tired at the moment.
If it struggles a lot in the spring consider a plant feed to give it a boost and if there are any signs of this leaf discoloration again chop a lump off and send it to the experts, either the RHS if you are a member or you can send it to us here at Ornamental Tree Nurseries, presuming you are in the uk.
Cheers,
Kate