Help needed to ID photo

[blueboy684]

Hi there,
I have been sent a photo by my brother who is trying to identify various aspects of.

Is anyone able to identify which Regiment the ladies belong to? I notice that whilst all of them have a stripe along the length of the epaulette a number of them have shoulder titles which I can't make out. I was thinking Nurses (QA's), or WAAC, VAD??

Secondly given the signaller in the centre of the picture wearing what looks like 1915-18 Overseas Service Chevrons (can't see if there is a darker 1914 one present) and only one soldier wearing a medal ribbon, is any one able to date this picture?

I have noticed the long service chevron and wound stripe.

Anything any one else can add would be much appreciated - is the chap with the receding hair line perhaps MGC?