They can be very secretive, and with good reason. M&B often do their best to hide their ownership. This was once an ancient coaching inn before they FUBARd it:
http://www.thebellgodstone.co.uk/
Own web address, a few sister pubs, just a local chain? But click on Terms and Conditions (ignoring doomed attempt by staff to look decorative):
http://www.thebellgodstone.co.uk/terms-and-conditions/ and the game is up.
Another example
http://www.homecountiespubs.co.uk/dukeofyork/ - again you might think they are a reasonably wholesome regional chain but click around a bit and you find they are related to Brunning and Price and thus part of The Restaurant Group, famous for such horrors as Frankie and Benny's and Garfunkel's. No wonder they keep quiet about it.