Thanks Thomas
Before posting, I read all of the similar threads in this subject, several of which you have replied to. I also read the links you provided, here and elsewhere.
The simple fact is that this behaviour or issue is something new to me too - hence I am looking for a solution. You never having experienced it doesn't really address my problem.
I'm pretty certain that the sites are indeed using JavaScript to redirect to the App Store. The JavaScript may be embedded in "rogue" adverts or content on those sites. But that does not change the fact that it is very irritating for the user and that it would be useful if it could be prevented without the need to entirely disable JavaScript.
I already know this has nothing at all to do with my network as I regularly use my iPhone on several networks and have seen this happen on all of them - including whilst on Vodafone's 3G network.