I can't help but notice that the Queen is apparently not immune from the 1999 Price Marking Order but she is from the 2002 Traffic Signs Regulations and General Directions. I was disappointed to hear this especially as the sign for the ladies' toilet in Kew Gardens gives a metric distance.
The Secretary of State can, at his discretion, suspend any part of the TRSGD. Since Her Majesty only acts on the advice of her Ministers of State, then, if that advice was to place a sign in metric units, it is quite legal since the minister is exercising his discretion to suspend the letter of the TRSGD.
Metre Man, if your opposition to me seeing it wrong to express metric walking distances is reduced to nothing than that then there can't really be a real pro-metric viewpoint that's worth listening to.
As I said to... Martin I think... you may as well save your electricity.
I'll be a devil and splash out a bit more on my electric bill.
Treat my jokey remark with contempt if you wish, but don't drag Martin into it. He made quite a serious point which you seem to have studiously ignored.