Thank you for your replies. I hadn't thought of the peas. This episode was quite bad and the poor dog had two days of pain and misery. I took her back to the vet yesterday morning and whilst she didn't think that there was pancreatitis she took blood, probably to shut me up. The results came back this morning and they are all normal.
She is now eating again and is back on her previous food. Fingers crossed that she will now be OK.
Chris - glad you got sorted with the food and hope that it is alright. I was helping a friend of a friend source a sub 20% protein food just yesterday. Her dog has renal disease. Think she went for the Skinners too. As for treats, I agree - some are very poor indeed. All mine get is sea jerky and a gravy bone at bed time. The sea biscuits sound very suitable for a bedtime snack.