Since she references the low postage of the 1930s in the first paragraph, probably pre-1935.

On Aug 16, 2013, at 12:36 PM, David Boyd <[log in to unmask]> wrote:

Anne Ridler was Eliot's personal assistant / secretary 1935-40, so was this other reminiscer earlier or later than she?

On 16 August 2013 16:09, Chokh Raj <[log in to unmask]> wrote:
T.S. Eliot’s Secretary 
The Editors 
LRB blog
8 August 2013