I would have thought that they would have to provide a proper company name, company number, address and so on, as your client now owes this company money.

I Googled and I thought it might have something to do with Blue Arrow, but I think that's a recruitment agency, amongst other things.

It could be Arrow Finance. 

For the purposes of research (in the hope that we might get a company name or some other information) I've just called the 0870 number and it is answered by a very unhelpful fax machine. 

I called the number before, 0870 4215410 and it has an American woman saying "This number is not in use. Goodbye." If that number belongs to Arrow and they are based in the US, then it could be Arrow Financial.

My journey has so far taken me to http://www.deweyballantine.com/contact.cfm?contacts=office

The lady there says that Arrow Global rent an office from them. She has given me the following number 020 7456 6115. Sadly though it goes to voice mail.

Dewey Ballantine is a multinational company following the link by Johnny Debt.

Nothing is mentioned about them renting offices to other clients but looking at what services Dewey Ballantine provide, I noticed it was the following:-

Acquisition Finance - representing banks, other financial institutions and their clients in a broad array of debt financing transactions.

Capital Markets - developing and implementing innovative structures for debt, equity, equity-linked, asset-backed and structured finance transactions, particularly in emerging markets

Energy - providing legal advice to participants in the electricity, natural gas and petroleum industries, from project developers, utilities, pipelines, producers and investors through to lenders and governmental entities

Mergers & Acquisitions - representing clients in complex international acquisitions, ventures and investments

Private Equity - acting for leading financial institutions and private equity houses in equity investments throughout Europe

Project Finance - advising on the development, financing, construction and operation of a wide range of capital intensive projects and facilities, we are widely acknowledged as one of the leading project finance practices in the world, and particularly well known for work in Central and Eastern Europe

Securitization/Structured Finance - advising an array of investment banks and other institutions in structuring financial products

Tax - providing U.S. and U.K. advice on the structuring of complex, cross border financial transactions, including M&A and capital markets transactions, as well as counselling multinational corporations on a wide range of international tax planning issues

It looks to me it could be their Acquisition Finance side of things maybe also trades as Arrow Referral as well!  The above information was taken from Dewey Ballantine's brochure here.

I always thought that if a company also trades under a another name then they had to declare it.  For example, our local card shop has a small sign in the window stating that the card shop is a trading name of another (bigger - i assume) company.

Even if Arrow Referral is not connected in any way with Dewey Ballantine then they must have a lot of money to rent offices in buildings like that in London.

The qucikest way to establish if they are a DCA is via the Office Of Fair Trading - Consumer Credit Licensing Branch, they will give you details held against the trading name in office hours. If they dont have a record then it isnt a Debt Collection Agency.

OFT CCL : 0207 211 8000

Just heard from Arrow Global, LLC regarding an MBNA credit card I'm paying of through a Debt Management  Plan administered by the Consumer Credit Counselling Service.

From what I can learn they're a bunch of Yankee newbies punting what could be a loan shark (www.blackandwhite.co.uk) and a debt collector Credit & Business Services Ltd., Hatfield Road, St. Albans.  That address sounds vaguely familiar but I could be wrong.

Have a phone number: 01727 731773.

Perhaps I'm going to extradited by a bunch of Yankee ****suckers who, as we all know, won World War II for which we had to pay them back every miserable cent they lent us.

Try Consumer Action Group for more info.