How often is the MacRobertson International Croquet Shield tournament ?
" Fri 6 – Tue 10 August " : Great Britain v USA at Bowdon , Greater Manchester and Australia v New Zealand at Heaton Park , Manchester " Thu 12 – Mon 16 August " : Great Britain v New Zealand at Nottingham and Australia v USA at Roehampton " Wed 18 – Sun 22 August " : Great Britain v Australia and New Zealand v USA both at SurbitonEach team is represented by 6 players and each test is the best of 21 matches comprising 12 singles and 9 doubles .