In answer to Maxtich's question, the sub 12 fpe version escapes the "only 22LR semis allowed" law because it is an airgun not designated as specially dangerous. Once the power is above 12fpe (or more correctly, capable of being over), the rifle no longer benefits from that exclusion and would - as it is written - be a prohibited weapon, i.e., section 5.
Now we all know that is illogical in the extreme. At one end of the semi auto spectrum you have a SA80 or a AK47 and clearly the man in the street is unlikely to be able to show good reason for having one of them, which is why they are prohibited. As you come down the power spectrum, the government of the day in 1998 decided that 22LR was OK to have, but of course it would be licensed as all 22LR rifles are. It's manifestly absurd to say that a rifle of one tenth of that power (approximately), a 12fpe airgun, is too dangerous even to be held on a licence.
Advice from the HO and from my FEO is to the effect that an air rifle is an air rifle; it matters not that a semi under 12fpe is a semi and not a single shot; despite the notional illegality we are allowed to possess without being prosecuted, that is what HOC68/97 says in effect.
So, if an air rifle is an air rifle, it is consistent and probably sensible to expect that a semi running at say 30 fpe would require a section 1 slot just as a Rapid 7 for example, of similar power. That may well be an outcome from the present kerfuffle.