I think there are some who nickname the 5-WES (Wessex Electric) (TOPS▸ class 442) units 'Plastic Pigs'.
These are 3rd rail EMUs▸ , but somebody left a copy of the Western Mail open for me which suggested that some of the class 442s might be coming to Arriva Trains Wales. Since we don't have any suitable rail electrification in Wales, this sounds rather far-fetched* (I don't think there's even any OHLE live yet although the installation in the IEP▸ depot at Swansea looked almost complete when I last saw it, which was some time ago now). Maybe Plastic Pigs can fly!
* admittedly, the article did state they would be hauled by diesel locos, but if they were going down that route surely it would be easier to use the tried-and-tested 67/68 + mark 3 combination rather than adding another type of train to the mix (unless they intend to replace the 2 mrk3 sets with 442s to eliminate slam doors, but the article didn't mention this).
The 442's are mk3 derived anyway (same body/frame/ trailing bogies) so they would not really be a different type of stock and would also be a quick fix for the slam door problem - if the fleet has been withdrawn now (certainly a few are listed as in storage), I suspect there will be considerable demand for them for future loco hauled (push-pull presumably) use, although they would need some conversion work to operate with anything other than Southern region control equipment. I seem to recall they were generally very popular with passengers and also that the reliability was very good latterly.