12 JUNE 1976, Page 15

Greene guile Sir: I was most interested in Mr Graham

Greene's plan to clobber the Post Office, and am endeavouring to put it into effect. Unfortunately,! am finding great difficulty in following his advice to 'post one letter a week to a friend in an empty unstamped envelope'. (My italics.)

When I have inserted a letter into the envelope it doesn't seem to be empty any more.

Perhaps it will come with practice. Nancy Wilkinson The Old Rectory, Kingston, Cambridge