Tinker, Tailor, Soldier, Notebooker?

Someone cut out this advert from a magazine for me recently. It's an MI6 recruitment ad - more about it here.

I thought it was quite interesting, but mostly I was intrigued by the text to the right of the photo - 'Sincerely Pooter'. What did this mean, I wondered - a test of spying skills, hidden code?

Later I found out that the person who gave me the advert had written these words to test out ideas for crossword solutions - nothing to do with the advert at all. I don't think I'm cut out to be a spy...

Book of the day here.