If the image is a bit difficult to decipher, here is a transcription:
The Foreign Office
6th April 1943
My Dear Reggie,
In these dark days man tends to look for little shafts of light that spill from Heaven. My days are probably darker than yours, and I need, my God I do, all the light I can get. But I am a decent fellow, and I do not want to be mean and selfish about what little brightness is shed upon me from time to time. So I propose to share with you a tiny flash that has illuminated my sombre life and tell you that God has given me a new Turkish colleague whose card tells me that he is called Mustapha Kunt.
We all feel like that, Reggie, now and then, especially when spring is upon us, but few of us would dare to put it on our cards. It takes a Turk to do that.
Sir Archibald Clerk Kerr,