How is employment experience considered in PhD funding decisions in the United Kingdom?
I help to run admissions for a DPhil (doctoral programme) in the social sciences at Oxford. Professional experience is of very minor importance during the admissions process (except where it has some truly central role in the research project). The four important things we give significant weight to are


academic transcript, 
quality of research proposal/statement,
admissions interview.
academic reference letters.


These will typically also be the main factors for funding allocated by the university (e.g. Clarendon, DTC). In particular, the panels that award these scholarships will have access to the same application material as the admissions coordinator, along with notes from the interviewer.

My suspicion is that a more vocational area might give more weight to practical experience. For example, someone with legal practice experience, or work as a laboratory intern might respectively have a bit of an advantage for a law/lab science DPhil. But the general understanding at Oxford is that academic excellent trumps all other considerations.