Ok I've done a bit more testing, and worked out that I could try and override the Data.AmazonProvider's OnExecuting method by putting my custom code at the top eg :
protected override void OnExecuting(Telerik.ExecutingEventArgs args, bool fireEvents)
String NEWS_FOLDER = ConfigurationManager.AppSettings[
String EVENTS_FOLDER = ConfigurationManager.AppSettings[
// Customised method to generate our bespoke thumbnail etc as required.
I then compiled it into App_Code and changed the provider name to my custom class (CustomAmazonProvider) by setting it in Web.config, like so :
However, I can't use it as I get a 'The given key was not present', which I'm guessing is to do with the code not being part of the Telerik libraries.
Am I on the right track here - I was so close to sorting it!