I would say alot of pro athletes take some sort of gear. World Records get broken literally all the time, in all sport disciplines. Now I'm not saying that this is because of PEDs, but I think they contribute.
HGH (Human Growth Hormone) is something I think many athletes take. Possibly IGF-1 (Insulin-Like- Growth-Factor-1) aswell. Both are anabolic, and neither can be tested for.
Another thing to mention is that AAS's are very expensive to test for. There are about 7000 anabolic, banned compounds out there. I doubt very much they have the ability or resources to test for all of them. I know even at high level natural body building they test for only about 200 most common.
...with these A Level results?