I had a similar problem, except mine would detonate at WOT. The problem was wires 7 and 8 were bad, chaged them and problem solved.

 

I understand the US and UK have different representations of octane ratings, the regular unleaded here is RON 95 and the super is around 97/8. I would assume the regular here is about the same as what it is in the US after you've converted the numbers.

The car always ran fine on the regular, but the super helped with the strange detonation problem once it set in. My car runs fine on the regular, i'd be amazed if sticking super in gave me any gains.

 

It finally threw a code today. 43. I went back and checked the voltage at the Knock sensor wire and it was fine....again. The knock module was a new one but untested. It failed the resistance test...ugh. Put another new one in and problem solved on the detonation issue. Thanks for the help fellas!

 

Excellent! The symptoms really sounded like no knock detection, so the solution fits perfectly. Glad you fixed it.

 

Thats what I first thought as well but after replacing the knock sensor I discounted it as being a possible prob until it threw a code and I decided to get the voltmeter out to double check. I have been driving it like this for 3 weeks now having to baby it around and today was the first time it threw that or any code. Now to iron out the 'other' prob it has when it gets hot and decides to sputter and pop out the exhaust and not want to rev over 1500-2000 rpm.