The double-yellow lines are not why the PCN was served.He has been walloped for parking off-carriageway, an offence in London since 1974 and which needs no signs or lines. The CEO could have done him for the double-yellow lines that apply on verges and footways, not just the carriageway, but which have two exemptions, (loading and boarding passengers), but off-carriageway parking doesn't.
However, there is a lot more here than meets the eye, because there is clearly a bay marked out by blocks : -
https://maps.app.goo.gl/NV5ErSBuYMpw3uSg6And it's obvious from GSV view over the years, that parking is allowed on that bay even though the double-yellow lines mean it should not be. If parking was permitted, then the DYLs should not be there, and there should be either a single-yellow if the bay is only allowed at certain times, or no line at all plus a sign for the bay. Your friend isn't however, fully in the bay, but partly outside it, hence the ticket, but if logic of the DYLs is concerned all the cars next to his should have got tickets.
Look at his car in relation to the drain cover and the bay. I think his car was partly in the bay. Others more expert than me will hopefully post more info on how you can prepare a robust rebuttal of the PCN, but do be aware that the council will refuse all reps, so he'd have to take them to London Tribunals, with the full PCN penalty in play. If he wins, nothing to pay, and if he loses, the PCN penalty is payable, but there are no other costs.
