Do single yellow lines apply after 6.30pm or on Sundays?

Yes, single yellow lines can apply for anything between 1 and 23 hours per day and also on Sundays.

 Double yellow lines always mean "at any time" and the need to have an accompanying sign was dropped in April 2003. Single yellow lines now apply for any restriction that is less than "at any time" and you must check the signs.

 If the sign does not mention days of operation it means that the restriction applies seven days a week.