I really don't know how many different versions of this HFT is being practiced in the UK as I have seen videos of some HFT comps on U tube with the shooters apparently allowed to fiddle with their scopes ala FT and with more freedom in their stance and kneeling postures, . Confused you will not be after this episode of the HFT SOAP.
When I and my shooting friends have an informal practice we tend to abide by the normal HFT rules regarding stance and scope. .
A.G