At first sight, it strikes one as another gold-encrusted piece of pointless extravagance, bordering on, I have to say, kitsch. And it cost an ‘undisclosed sum’, which means ahelluvalot. So my immediate response was disapproval, have to say. But but BUT, the Diamond Jubilee State Coach, known Down Under as the State Coach Britannia, is a treasure trove of surprises… and I…