Well, if you go back a decade, I doubt that neutering was being done (by the RSPCA), at such a young age. Clearly, over the years, they have discovered that perhaps, early neutering offers more advantages than disadvantages. This is showing that some strategies are being adopted, while the older "antiquated" techniques are being ditched.
The strategy of early neutering will almost certainly have been adopted by looking at data/results from other countries who are happy to neuter at an earlier age.
Oh and yes, there are techniques/strategies that are "antiquated" and still being used in the UK, in many areas of life. As older generations die off and newer/younger ones take over, things generally improve for the better. This is a fact (I can give many examples, in particular, economics and medicine). I know some people like to think that the old ways are/were always the best, but most of the time I dont believe this is the case. Like I said earlier, it is important to move with the times - the RSPCA seem to have done this, at least with regards to feline neutering.