You have found an extinguisher from BWH who exclusively manufacture for London Securities, in other words Nu Swift, TVF, MK Fire and many more.
Although Kitemarked it does not technically meet EN3 due to the colour, nor does it meet the UK derivation allowing limited colour coding (implemented in BS 7863)
When they changed the servicing standard BS5306-3 in 2009 there was to be a clause that would result in these extinguishers being condemned as the colouring could confuse a user.
However, the BS5306-3 committee includes manufacturers including London Securities. Because this change would scrap every foam extinguisher installed across the group for the last 5 or 6 years they objected and because a unanimous vote is required to pass a standard it was in limbo for the best part of a year until everyone else backed down and the clause dropped.
The other user of Green labels, TOTAL had accepted the clause, relabelled new versions and produced replacement labels for existing equipment without any objection or fuss.
It's a stored pressure 6 litre biodegradable foam extinguisher with an impressive 27A 183B rating (BWH do a 9 litre water additive with a 43A rating as well!) and will set you back £180 from the MK Fire end of the Group to nearer £300 for the GFA/Nu Swift end
