thumbtacks in road

I would like to warn of tacks in the road in London/Surrey, specifically from Hampton Court bridge headed toward Walton. The tacks are mostly brass coloured but some silver, and are also on the footpath. I also encountered tacks day before yesterday in the cycle lane between Hersham and Esher, especially near the Bourne river, but I think I have picked up most of those, amounting to a good handful. There were also a few between Esher and the North Downs, possibly carried along by motorist tyres. So be aware and help pick the rotten things up, it’s not my job either.