Registered Envelope used in London with CamberwellGreen dated stamp sent to Brixton.
Franked at the 5d rate with sg 44 penny plate ( H L ) & Scarce on cover Sg 152 - 4d Vermilion plate 15 ( J K ) both cancelled by London S.E. 1 South East District DubusType 12 Rarity H = very few exist.
See also red Registered S.E.D.O. date stamp.
Cat Value on cover just for sg 152 = £1,000-
 
Condition overall very good.