This is very unlikely. In English law, for someone to be held liable it would have to be shown that the intervention had left someone in a worse situation than if there had been no intervention. In the case of a cardiac arrest under discussion (i.e. someone is technically dead following a cardiac arrest) it…
There is currently no legislation in place to make AED’s mandatory in the workplace. There are efforts being made to promote the introduction of legislation to make the provision of AEDs mandatory in the workplace, schools, sports venues, and certain public buildings (UK Resuscitation Council, 2013)