Thanks MR, appreciated - I have been BF as normal, and only giving two small solids feeds in the morning and late afternoon

I was wondering if the farex was the issue, but I only introduced the potato on the weekend (sunday) and it was yesterday that the poo changed so the timing is right to suggest the potato might be the key, I might just stick to pumpkin for the next few days, He seems fine on banana (it was really ripe)