Trooper Albert Richards: 'Impossible to write at present'

One of a series of hand-drawn postcards by Trooper Albert E. V. Richards of the 10th Royal Hussars (Service No. 1936), addressed to Miss M. Rust, Orchard Hotel, Portman Street, London W. It reads:
[Front]
Impossible to write at present
A.R. 1916. X.R.H.
[Reverse]
O.A.S.
14th Sept. 1916.
Dear Mary,
Many thanks for Ink and post-cards sent some time back. Will do my best to send letter later on. In good health and trust you keep the same. Albert.

Postcard from the collection of the website owner.