Running

May sound silly, but had you considered one of those telephones designed for the elderly, with a panic button on? That combined with GPS would probably be more useful than a flare gun/similar.

I had considered an information wristband. Like those used by people with medical conditions. Just in case I'm knocked out, and mistaken for a local.

'Attention this person is English, and as such has likely paid no heed to conditons or terrain, is almost certainly grossly underdressed, undernorished, dehydrated, and probably lost'

I read all the time of some local getting caught in storm while ski touring the mountain tops. digging a survival hole with their belt buckle, and surviving on 2 kitkats for several days.

You also read of forrins like me being heli lifted off mountain sides, an hours walk from home, in fine weather*.

(*happened to an aussie mate last year in fact)