Our Fire Safety Regulations (NI) 2010 do not permit the use of sliding doors as emergency escape doors. I understand statutory regulations elsewhere in the U.K. have similar stipulations. The requirement seems to be widely flouted. I note many designs/FRAs referring to the need for fail safe operation but the regulations don’t have caveats that would support their use in any situation. 
Any views?

Whilst they are in deed Regulations the current regime stems primarily from an intention to deregulate fire safety - this is one of the consequences. You just give your advice you feel comfortable with, it will be followed or not, it's the way of things it seems!