The writer of the first guide is giving you the best info,  Recovery Trucks need to be MOT'd as VOSA reg's are a nightmare   ie, spec lifts only are exempt but can only be used for roadside recovery/travelling to a recovery or returning from one,if you get caught shopping,going to the chippie for lunch etc etc,you can be busted.  Tilt/slide trucks same scenario but anything on the back must be incapable of moving under its own power,if it starts,drives and runs you can end up losing the truck and the vehicle on the back,that also applies to 7.5t so if your caught carrying a scrapper,defined as a scrapper and therfore not a breakdown/recovery its bye bye truck from the nice gentleman from Vosa.

The moral being,upto 7.5t make sure its got Mot, 7.5t get an operators licence,then provided your not nicking cars your pretty well covered. Besides,try persuading your insurance company its Mot exempt but still roadworthy,,,,,,,,you know what their like              NO MOT,,,,,,,,,INSURANCE INVALID