Rare metric signs. 

Are metric signs in metres really rare and illegal? There is one near my house that is in metres. Could someone confirm if they are actually rare. Here is a google maps link to a sign in emtres near my house. https://maps.google.co.uk/maps?q=ll26&hl;=en&ll;=53.129419,-3.777752&spn;=0.036513,0.104628&sll;=49.5,22&sspn;=40.673602,107.138672&hnear;=LL26,+United+Kingdom&t;=m&z;=14&layer;=c&cbll;=53.129405,-3.777621&panoid;=458KEwkq2_2Vwbuo0J7RPw&cbp;=12,260.66,,1,5.49