If the Union Jack is accurate, you'll be able to tell which way is correct by the flag pattern. Flying 'The Jack' upside down is a sign of distress - which you don't need at Mallory Park!
For info: The Union Flag must be flown the correct way up. This is with the wider diagonal white stripe above the red diagonal stripe in the half nearest to the flag pole. The wider diagonal white stripe should be above the red diagonal stripe at the top left hand side of the Flag nearest the flag pole.