By law if they are via an agency they pretty much have to tell you the name of the hirer - below is the exact section of the law (often ignored by even the largest agencies as the law has few teeth)
In the 27 years I was in recruitment (which goes back to before the current law even) I only ever twice sent a cv to a client without the person knowing the name of the hirer - once because the legal practice in question were about to fire someone for gross misconduct (misuse of company IT systems) and wanted to have a replacement IT Sys Admin lined up and I was only allowed to say "A large leading regional legal practice" and once for a graduate trainee where his mum gave permission as he was at a festival with no mobile reception.
For clarification, legally perm recruitment is via an
Agency and temp via a Recruitment
Business
These Regulations revoke the Conduct of Employment Agencies and Employment Businesses Regulations 1976, the Employment Agencies Act 1973 (Charging Fees to Workers) Regulations 1976 and the Employment Agencies Act 1973 (Charging Fees to Au Pairs) Regulations 1981.
www.legislation.gov.uk
Excerts
Reg 21 -
An agency or employment business shall ensure that at the same time as—
(b) it offers a work-seeker a position with a hirer—
(i)it gives to the work-seeker (whether orally or otherwise) all information it has been provided with about the matters referred to in paragraphs (a) to (e) and, where applicable, paragraph (f) of regulation 18; and
unless the work-seeker or hirer requests otherwise.
Reg18
(a)the identity of the hirer and, if applicable, the nature of the hirer’s business;
(b)the date on which the hirer requires a work-seeker to commence work and the duration, or likely duration, of the work;
(c)the position which the hirer seeks to fill, including the type of work a work-seeker in that position would be required to do, the location at which and the hours during which he would be required to work and any risks to health or safety known to the hirer and what steps the hirer has taken to prevent or control such risks;
(d)the experience, training, qualifications and any authorisation which the hirer considers are necessary, or which are required by law, or by any professional body, for a work-seeker to possess in order to work in the position;
(e)any expenses payable by or to the work-seeker; and
(f)in the case of an agency—
(i)the minimum rate of remuneration and any other benefits which the hirer would offer to a person in the position which it seeks to fill, and the intervals at which the person would be paid; and
(ii)where applicable, the length of notice which a work-seeker in such a position would be required to give, and entitled to receive, to terminate the employment with the hirer.
And
Advertisements
27.—(1) Every advertisement issued or caused to be issued by an agency or employment business shall mention in either audibly spoken words or easily legible characters the full name of the agency or employment business, and whether the services it advertises are those of an agency or an employment business, as the case may be.
(2) Neither an agency nor an employment business may issue or cause to be issued an advertisement about positions which hirers seek to fill unless the agency or employment business has—
(a)information about specific positions of all types to which the advertisement relates; and
(b)in relation to each such position, the authority of the hirer concerned to find work-seekers for that position, or the authority of an agency or employment business, which has such authority to issue the advertisement or cause it to be issued.
(3) An agency or employment business shall, in every advertisement for work-seekers issued or caused to be issued by it in which rates of pay are given, state the nature of the work, the location at which the work-seeker would be required to work, and the minimum experience, training or qualifications which the work-seeker would be required to have in order to receive those rates of pay.