Thanks for that, Q31 tallies and she used another name - Planudes. She certainly worked out of the Firth of Forth along with the armed trawler Quickly (aka Q32, Carolina, Master, Sinton and originally H99 Swift)
The info I've got to date puts her in action as ' a disguised armed trawler' on 20th June 1915 near Bell Rock and there is a further note from April 1919 that she was 'disguised as coastal steamer'
The disguise may have been structural but could just have been canvas panels.
Tony