
Could have done more research but not worth it for a half hearted Benny Bargey.
data.ncvo.org.uk/a/almanac17/workforce-3/
data.ncvo.org.uk/a/almanac17/workforce-4/#Workforce_and_organisation_type
( , Mon 4 Dec 2017, 15:20, Reply)

Thought the number was large enough to point out it couldn't be nationalised without muddling things with workers that work for free a few times a year or month.
But here you go.
data.ncvo.org.uk/a/almanac14/how-many-people-regularly-volunteer-in-the-uk-3/
( , Mon 4 Dec 2017, 16:14, Reply)