Re: a lot of companies at that address.
Correct; as another expert has already noted, it's quite common (and often reasonable) to have distinct "trading addresses" and "registered offices". Registered offices frequently end up being accountants, or similar.
That's one of many reasons you need to be careful who you're doing business with, hence my comment/query re Tax Return(ed) Limited.
A "company number" is meant to uniquely identify any particular England+Wales registered company. Even if a company changes its name or changes its address (as frequently happens) the company history should be traceable back via the Company Number; these are all published and freely available pieces of information (at the moment - this time next year, they'll probably be "unnecessary EU red tape").
Quite why company name/company number/registered office isn't a big part of the latest banking proposals for "safer transfers" is a mystery to me - these are readily checkable by bankers and public and could help prevent many of the "I paid £x000 into someone else's bank account and it wasn't the right recipient" stories which hit the meejah from time to time.
Biting the hand that feeds IT
