Yes there has - but only affecting full auto's as far as I recall from reading an airsoft magazine article recently. Its a dangerous change for the hobbyist because it means that at a stroke you can be in posession of a firearm.
I'll try to find the article and report further if no one else can give a definitive statement.
Its the Policing and Crime Act 2017, Section 57A, by the way. It restricts the power permitted for an airsoft gun that can discharge two or more missiles successively with a single press of the trigger, to 1.3 joules, whereas any other airsoft gun can be up to 2.5 joules.
Ironically, a copy of the Act itself costs £40 - more than many airsoft guns!