Are you aware that parking off-carriageway has been an offence in London since the 70s ? No signs or lines are needed, it is an absolute ban. However, if a council decides the street is wide enough, then it can pass a resolution to allow parking off carriageway for named streets. Most of these only allow the vehicle to be partway off the carriageway. Looking at where you parked, it would seem very unlikely the council would allow parking where you parked, you were basically blocking the whole footway. I also see no signs or marked bays that might indicate such parking is allowed.
Anyway, when you've posted the PCN, fuller advice can be given. There are many possible "technical" issues that can arise with a PCN and the legislation under which it is issued, so I'll hold off for now.
Sorry if this isn't what you would have liked to hear, but we have to deal in reality on this forum.
