Watch List notes:

Hong Kong Medallic Cover 1986 Masterpiece Edition - Official Opening of the New Headquarters of the Hong Kong Bank (7 April 1986) comprising Gold Medal 38mm diameter, 38 grammes of 22 carat gold Lustrous UNC, on the commemorative envelope of issue with Hong Kong $1.70 stamp both showing the new building, number 5 of only 500 sets produced, in the red folder of issue

Estimate: 1500-2000 GBP