Hello, I am Keith, one of the experts on Just Answer, and pleased to be able to help you with your question.
You will find the relevant boxes for completion on the SA100. They are the first items under 'Income' at the beginning of the form and cover most investment income. If you have property or foreign income you will will have to complete SA105 & SA106 respectively too.
I do hope that you have found my reply of assistance.
Yes it is foreign income. I had exactly the same thing happen to me some years ago with one stock market investment. HMRC drew my attention to the situation and corrected it anyway so I got it right the next year. It didn't, as my old boss was wont to say, alter the price of cheese in any event!
Thank you for your support.