TBF they probably not even considered the Airgun as being a legitimate tool for pests, more likely considering it an older youths tool for pot shotting.
A much more sensible thing, would be the person with permission, or a landowner could use the power he likes power to get the job done, but the rest limited to 10-11
Most on here seem to favour 10.5 as being ideal for FT anyway …even if i would prefer much more for hunting.