It's the newest signage standards, introduced to reduce the national deficit.
Alert councils have realised that reducing excessive speed on roads by installing speed cameras, paying traffic police, making major changes to infrastructure, and all the rest, is extremely expensive - and a long drawn out process too, dealing with all the objectors.
There is of course a very much cheaper option, as here
Use cyclists to reduce the speed of other road users. They're cheap, expendable, easily replaceable, and nobody likes 'em! BINGO!
Oh dear - I am getting cynical in old age.