Yeh after various googling I found the same information, from the man Andy F:
Ignition timing This is determined mainly from the MAF sensor and the engine speed. There are maps for high octane and low octane fuels and the ECU selects between them depending on knock sensor activity. The ECU also learns ignition timing from the knock sensor and effectively sculptures these maps over time. Pre 1999 models !Removed! the timing in an area of the map if the knock sensor was ever active. 1999/2000 models will try periodically to advance the ignition again. 2001 and later models run very actively on the knock sensor and adapt very quickly. The practicality of this is that resetting the ECU should be performed on pre 1999 cars if a higher octane fuel is used or if just recovering from a tank of “bad fuel” as sometimes happens. This will enable the ECU to relearn more appropriate ignition timing for the present fuel. It is not worth resetting later models. On 1999/2000 models, typically after twenty or so miles, the ECU has adapted quite a lot. There is no need with any car to excessively load the engine on the brakes or by putting four heavy blokes in the car and driving up long hills. If anything excessive load will only expose the car to more detonation and it will learn more pessimistic ignition timing!