Central Bank of China, a uniface obverse composite essay of an unissued design for 300 yuan, c.1944, grey

Central Bank of China, a uniface obverse composite essay of an unissued design for 300 yuan, c.1944, grey, Sun Yat Sen at centre, denomination at each corner, red seal signatures at left and right, a very unusual denomination and no issued 300 yuan notes were every issued bu the Central Bank of China,
(Pick not listed), PMG 66EPQ Gem Uncirculated. A beautiful piece mounted on thick card. Unique