Hi Fixer,
Well I've attempted to look at a few different options to help you in your research and it would be great to find out more information because It's so fascinating to learn about soldiers lives.
I've searched the CWGC to check if any Hook of the R.A. was killed during the war but found no suitable match.
I've searched the Medal Index Cards for any suitable match but again no luck.
I don't think Officers service records have been transcribed online and are held at the National Archive in Kew but to be honest all my ancestors never reached above the rank of NCO so I haven't researched any Officers.
The only advice I can offer is to post on a specialized site where maybe some R.A. boffin could help further:
http://www.1914-1918.net/notes.htmThe above site gives lots of general information on the War, researching individuals and also a link to their forum.
Good luck and it would be very interesting to hear if you do find anymore information.
Kind regards
Adrian