http://www.famousvulcans.co.uk/xh537.htm
'8th May 1978
Delivered to 27 Squadron as a Vulcan B2 MMR. The MMR role was to maintain a alert standard through out the North Sea, keeping an eye on the UK`s oil fields and acting as a early warning for any USSR ships entering our waters. As well as that 537 would pick up any distress signals from ships, something that the Nimrod does these days. 537 could also be fitted with air-sampling pods, a task inherited from Victor SR2s of No 543 Squadron.'
take a look