As I have said many times before, there is no justification for using signs that could be misunderstood and misleading. The Responsible Person should be told this as a significant finding of the risk assessment, if he wishes to ignor this fact, or justify their use because of Government confusion he can.
As we are all aware nothing in Fire Safety is prescriptive, there are many ways you can acheive the same objectives in Fire Safety so it is possible to make up any sign you want to and it is totally legal to do so. Even for the provision of emergency lighting government guidance tells us a torch readily available can satisfy the legislation.
Euro Signs are not understood, as a fire safety professional I can not accept they can satisfy the requirements for escape route location, identification or directional guidance for evacuees, no more than I can recommend a torch for emergency escape route illumination.
Without wishing to offend any one, It is a matter of professional competence, integrity and above all liability to promote and recommend best practice, any deviation should bring benefit not detriment.
BS 5499 Part 4 2000 for Escape Route Signs, ISO 7010 is the best possible solution.