It looks like a sheet of stamps, but is it?
"I don't know about a sheet but the design, including the "label" (which is really the title) was used for the cover of presentation book issued by the Post Office in 1972 on the Queen's silver wedding anniversary. See the text for CP4 on page 6 of Appendix 11 of the Deegam Handbook. Only 2000 such packs were issued."
This forum has been running now for as long as this blog and has some really good discussions with valued information on the Machin definitive. I do not know why but it has gone a little quiet of late. hence this little plug
If you are not yet a member and would like to contribute, or just ask questions here is the link to browse and or join.