This £10 first class single MAN to YRK ticket http://www.brfares.com/#faredetail?orig=YRK&dest=MAN&grpd=0438&rte=85&tkt=WDU has restrictions, but it is a bit ambiguous: is it only valid on Sundays but not Saturdays, or not valid on Sat and Sundays?
I can't find it on the TPE website at all.
I can't find it on the TPE website at all.