I had a 'look like a spanner' moment in a city centre post office at the self service till. Just bought some stamps, hit the 'pay with debit card' and then stood there like a lemon with my watch over the contactless reader... Given I've paid for stuff in my village post office with no bother, they either haven't enabled contactless on these self service terminals (I tried my card as well before resorting to chip & pin) or the counter staff are pressing a different button to enable contactless that can't be currently done at the self service terminals...