"PARKING ON YELLOW ZIG ZAG LINES
It is possible to park on yellow zig zag lines legally under certain circumstances:
YELLOW ZIG ZAG LINES WITH SIGNS
Yellow zig zag lines outside of a school that have signs erected to inform motorists of the hours of operation will have parking restrictions that are enforced legally by local councils. Signs must be placed near the yellow zig zag lines to allow a Traffic Regulation Order (TRO) to be effective and will provide the local council with powers to issue a Penalty Charge Notice (PCN) by use of CCTV or Civil Enforcement Officers.
Motorists are legally permitted to park on the yellow zig zag lines outside of the hours marked on the signs, unless other road markings indicate otherwise (see below for further details).
YELLOW ZIG ZAG LINES WITHOUT SIGNS
Yellow zig zag lines without signs to accompany them do not have a Traffic Regulation Order giving the local council powers to issue PCN fines. Therefor it is technically legal to park on yellow zig zag lines without signs at any time.
However, these zig zag road markings are placed there to advise motorists not to wait or park on these lines for the safety of children and although the local council do not have the powers to enforce penalties, police frequently issue tickets in such cases.Tickets are issued on the grounds of causing an obstruction to either other motorists or pedestrians and not for parking on the yellow zig zag lines directly."
It might be worth contacting the school headteacher and your pal's local councillor about the parking situation, asking the councillor what can be done to get a TRO issued or getting police to visit the school now and again.