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The Corgi registered gas fitter who came to install my new gas fire said that by law (his words, not mine) he could not install the fire until I had obtained a certificate from a NACS registered chimney sweep to confirm it had been swept. So hopefully that answers Ethel and terambulan. Although I don't remember mentioning or asking for details as to which law this relates to or log fires.
I have now booked one and the cost will be �35. So thanks to mcandrew and spudqueen.
Once again I, like so many others, have suffered the eternal problem with this website in that only 50% of the answers submitted actually answered my question.