If there are double white lines in the centre of the road,broken or otherwise,parking is not permitted.Sorry.
Solid Center lines mean "No Crossing the line" nothing about parking. Normally these line co inside with Solid white lines along the side of the road. Which mean no Stopping or parking on the carriage way.
I was looking if there was a reference to parking distance from the crossing like a zebra crossing. But i'm not seeing one.
If you were parked where these 3 cars were i can not see the problem, as the line in the center of the road is broken on there side which means as a motorist you can cross (no problem) how ever if you were on the other side then it "could" be a problem as the line is solid in the center of the road and if there was not enough space then cars may have to cross that line. But i don't see that being your problem as they should have "No Parking" Solid white lines down the side next to the pavement, as long as that center line is. But food for thought is that if there were white lines at the sides that would mean no stopping or parking on the carriageway.
Ref : Level Crossings http://www.ukmotorists.com/highway%20code.asp?s=Railway%20level%20crossings
Ref : White Lines http://www.ukmotorists.com/highway%20code.asp?s=Lines%20and%20lane%20markings%20in%20the%20road#900
108. Double white lines where the line nearest you is solid. This means you MUST NOT cross or straddle it unless it is safe and you need to enter adjoining premises or a side road. You may cross the line if necessary to pass a stationary vehicle, or overtake a pedal cycle, horse or road maintenance vehicle, if they are travelling at 10mph or less.
I think the wardens are getting you on a unknown ?
No signs or warnings.
Personally i think you have good grounds for an appeal if your parked where the cars are in the picture, as i can not find any reference to distance from the crossing (But may exist).
Another Source of info : http://www.direct.gov.uk/en/TravelAndTra...e_levelcrossing
But no Reference to Distance from the crossing.
I think your going to have to look at the lamp posts for any local no parking laws that may apply.
There are no "Keep carriage way clear markings (Solid white line near the kerbs) so you dont need to worry.
Hope that helps.