A compentnet person would check the cable at the shed end as part of the testing and see that the cable is of a reduced size at the shed, and even more so if the cable changes from T&E to SWA.
but thats kinda my point. there are too many people who are not.
you cant tell me youve never gone in to a house where they have done what i have suggested?
i think for safety sake it is what i would do, reg or not.