Three London authorities (TfL, Westminster and City) have got authorisation for identical worded signs that say in black lettering on white, on either 2 lines or 4:
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Click here for Westminster’s. There are some unusual conditions attached to some of these authorisations. TfL may not display more than 50 such signs; the 2017 City authorisation (but not the 2019 one) only allows the signs to be up for 18 months.