It is worth noting, that MBI's are underwritten by Insurance Companies. For example, Autosure MBI used to be underwritten by VERO, though is now underwritten by DPL Insurance.
Essentially, it's all one big melting pot of insurance, from Motor Vehicle cover, to MBI, to Home & Contents, to Public Liability etc etc. View them as departments covering different things within a given company, if you like. Insurers all, and before they go on a date with you, they want to know that you've been good to your previous suitor. and the one before. and the one before... ?