Post Office 1970 colour ink trials for 1970 Philympia Exhibition cancellation

Post Office 1970 cancellation colour ink trials for 1970 Philympia Exhibition issue. Two Different Literary Anniversary 1970 FDC both inscribed Cancelling inks for Philympia one noted colours submitted to R A G Lee for approval with specimen impression in 7 different colours. The other cover notated Chosen Colours (black and blue to be deeper).