When I did recovery I was told that to recover to a place of safety then no ADR was required, but for an onward journey ie to a repair shop/back to the vehicles base then an ADR qualified driver needed to be present either as a passenger or in the form of the recovery driver himself.
The information I was told could also possibly be incorrect as a lot (certainly the one I worked for) of operators are cowboys, but I didn’t give it much thought as at the time I still held a valid ADR so it didn’t affect me.