Dave Cousins, Dave Lambert and Brian Willoughby of the Strawbs released an album in 2001 entitled Baroque & Roll, largely comprised of acoustic versions of previously released Strawbs songs. They called themselves Acoustic Strawbs and periodically toured under that name, with Willoughby sometimes being replaced by Chas Cronk (who like Willoughby was an on-again, off-again member of the Strawbs).
Cousins and Willoughby also released a pair of albums as a duo. The first one was released before Willoughby had ever played on a Strawbs album, but the second one was released some years after.
And then Cousins and Rick Wakeman released a studio album together in 2002 entitled Hummingbird, though Wakeman, a former band member, was obviously long-gone from the Strawbs when that album came out.