plus oxfords website says they consider A* equiv to 8/9
It's under the GCSE tab
7 is considered an A, 9 is considered above A*, so use your common sense.
It covers the ground between a 7 (which is the old A) and a 9 (which is above an A*). Officially, it covers the top of an A up to probably about the middle of an A* but the general consensus is to accept it as an A*. Most universities and sixth forms treat it as an A*.