Many thanks for the second opinion. You were correct.I wouldn't say that's irreparable personally. It's well away from the sidewall which is usually the deciding factor, and so long as it hasn't been driven on when flat, it should take a plug no problem.
Try another tyre place.
Took the wheel off and drove it round to someone more knowledgeable - 15 mins later it was fixed.
Thanks to Chiltern Tyre & Exhausts.
