Field Marshal Montgomery drawn by my father

I am blessed with a lot of really lovely nieces,one of them sent me this portrait of Field marshal Montgomery she had in an old scrap book. It's a great find,it rang a bell with me for I remember seeing it when I was a boy.Grimey was a master of the quick sketch,he could draw a portrait from memory.When we lived in London he would sometimes take us out to Kensington Gardens with sketch books,sit on a bench,watch people walking by then have to draw them from our observations after they had passed. He always got it spot on for both clothes and faces,even type of gait !