It is hard to think of any investment that generates a higher return for the whole economy than bringing military capability up to the necessary level. On his departure from Britain, the Polish ambassador made some valedictory observations that struck a chord with me. After three years in the post, Piotr Wilczek wrote in an article for the Daily Express that he leaves a country with functioning, if imperfect, public services, a trusted judicial system, free media and peaceful handovers