The Strawbs. Strawberry Music Sampler No.1
1969 publicity limited edition promo album at the time and 99 pressed. Only two copies have surfaced since that time.
The Strawbs first commercial album was produced by Tony Visconti. The tracks for their proposed first album on A&M had dialogue links between the songs, but the concept was dropped when another group released an album using the same idea. Various CDs were released in the 2000s.
Update
I see another has surfaced and sold in 2021. I have met Dave Cousins many times and talked about this LP. At the time of The Strawbs article in Record Collector only two copies were known to survive, so now the total is 3. This one sold for £2,500 on Discogs.