There seems to be a shortage of public toilets where ever I go. TFL and British Rail tend to be the best, and the worst are in London generally, unless you fancy a pint of beer.
To add to the list of publicly available toilets are those at Trafalgar square, and also those in St James’s park. Thank you.
This is in addition to those at Covent Garden, Guildhall, London museum (when it is open), Liverpool street, Fenchurch street, Charing Cross, etc.
Generally, London is pretty rubbish at providing public toilets. I blame the Mayor for this, not the current mayor, but the one who now runs the country.