A half-remembered snatch of poetry has in recent weeks been drifting in and out of my mind, and with it has come a dull ache - a sort of numbness and sadness combined. It is I know the first line of a piece by the late, great British poet Stephen Spender. It goes like this: "I think continually of those who were truly great."

Perhaps the sadness has something to do with the fact that in the July just gone, three extraordinary individuals from a bygone era - the Battle of Britain - have left us.