i) HFA does not subscribe or allow ‘Captive Bolt’ stunning, as the procedure is not reverseable and the animal dies prior to slaughtering, ii) Low voltage electric (tongs or water bath) stunning is used only to immobilize the animal or the bird, with the assurance from the OVS that animal are not dead prior to slaughtering, iii) Mechanical slaughter is also used with strict presence of Muslim slaughterman/men, wherever manual slaughter is not in operation. Muslim slaughterman/men would do rendition of shahadah all the times whence slaughtering is in progress. Blades are NOT blessed, as some rumours are purporting and circulating.A document which is labelled Guidelines for Slaughter (this is hosted on HFA's website)
Once again here is the link:
Was not able to fully read all the details but just the fact they allow mechanical slaughter is reason to either try to convince them to move away from this practice or look for a more viable solution. Such as the HMA in toronto.
Last but not least here is further information about Halal Food Authority uk:
Halal food authority
109 fullham Palace Road
hammersmith, W6 8JA
44 0 844 879 4568