This is doing my head in and needs better brains than mine.
JSA reg 140 says a person in a vulnerable group is a claimant who...(k) is a person
(1) who...was being looked after by a LA
(2) with whom the LA had a duty...to keep in touch, or
(3) who...Qualified for advice and assistance from the LA
but in respect of whom 1,2 or 3 above had not applied for a period of 3 years or less...., and
(4) ...is under the age of 21

I read this as saying that a "care leaver" under 21 is in a vulnerable group if they "left care" over 3 years ago. However the commentary in Mesher and Bonner appears to say the opposite, i.e.
The categories (vulnerable groups) are
(10) a person under the age of 21 who was being looked after by the LA....within the last 3 years.

Help!

C'mon you legal eagles, no response to this one yet. It's Friday afternoon and you deserve a spot of light relief.

OK Brian - more is less

I ain't no legal eagle but if Regulation 140 read "...but in respect of whom, 1,2 or 3 above had not applied for a period of 3 years or more..." then you would be right, but it don't. Just to reassure you further Mesher and Bonner are also supported by CPAG Handbook p449 and paragraph 35135 of DMG Volume 6. Hopefully you can now sleep easier.

Many thanks

Shaun