I remember back in the late 70's being on a class 50 (?) hauled rake of a cross-country service being stopped between Coventry and Birmingham International by a failed local EMU▸ ahead of us. After about a 30 minute delay we simply drew up to the rear of the failed unit under caution, and then slowly propelled it into BHI. Caused less than an hour's delay. All the buffers and couplings matched in those days.
I think that was a well-rehearsed move back then as I had an identical experience between Smethwick and Wolverhampton. One of the down-sides of the breakup of the national system into self-interested companies is that as well as the technical difficulties of getting different types of stock to engage with each other (I use that term as computer systems are involved as well as physical couplings) there are more complex communication systems between the various companies to agree such a move even it was possible.