For me the height of the signs is tantamount to poor positioning. On approach it is likely the signs will disappear above the windscreen. Whether this would win at London Tribunals is, of course, unknown; but would be a gamble as it is subjective. Certainly the council will never give way, as they get to keep the penalty money.
Please post the PCN, all sides, redacting only name and address. Using a satnav in London these days is not recommended as there are restrictions like this all over the place, and satnavs are never up-to-date. You might have the very latest of latest versions but if the base data is out-of-date, you will still get misdirected
