The two agreements struck by Britain and France on defence co-operation this week have not brought citizens out on the streets of Paris. There were worries – expressions of anger even – about Sarkozy’s decision to take France back into Nato’s integrated command structure last year, but this is different. The fresh-faced Cameron and the embattled, less rosy-cheeked Sarkozy are like two sons whose parents have frittered away their family fortunes: they must now find common cause and drastic economies, which means moving in together if they wish to remain in the ritzy part of town reserved for big military spenders.