Thanks Nick,
The Naval Air Service, Vol.1, 1908-1918 by The Naval Records Society, pp.712/15 has part of a report on RAF in Med 1918. It appears to discuss anti-submarine patrols, but the relevant pages are not reproduced. I may have to get it from TNA.
Regarding ‘the pilot concerned merely regarded all ASW work as Spider Web patrols ?’
Possible, as he did a lot of them and there is only this single mention of Spider Web. The patrols often turned into convoy escort so a strict Spider Web patrol does not really fit.