Sorry I gave a sloppy answer which was probably not helping !
Broken down into points
IF you are "placing on the market" - that is according to FSA anything that goes beyond the consumption by the owner or that of members of their immediate family living there - then you must use an approved slaughterhouse - and mobile ones of these would be expensive as they would need both the state vet and meat hygiene service.
If you are only having for consumption by you and your immediate family...etc. then according to the FSA you
cannot use a mobile slaughterhouse to both kill and dress you carcase. They successfully prosecuted "Lesstress" who were offering this service in Cornwall. However Lesstress appealed and the ruling was overturned on a technicality. Lesstress continue to operate (
www.lesstress.co.uk) and have not been prosecuted again - probably because it is too much hassle - this doesn't mean it's legal, but does indicate that the Cornish TS don't plan to take any further action. Another TS might take action if someone started up elsewhere than in cornwall - after all the legal point was won for that case.
What the FSA refuse to be clear about is whether paying an itinerant slaughterman to do the actual killing is legal as long as the owner does the butchering. Their 2006 guidance stated "
If, however, the slaughterman did no more than kill the animal for the farmer, leaving the farmer to dress and cut the carcase, the Courts might be less likely to conclude that the slaughterman was supplying goods (and more likely to be supplying services). If so, this activity might be held to be
lawful, (i.e. neither the Hygiene Regulations nor the TSE Regulations would prohibit it) although the issue is far from clear." The 2009 and later guidance simply omitted this sentence leaving the original one that says " It is
unlawful for a farmer to use the services of an itinerant slaughterman both to slaughter his animal and to dress it " leaving the question of "or" rather than "both" hanging neatly in nowhereland.