Cover image not available
Mortimer's tie. Originally published: London : British Broadcasting Corporation, 1976 - The spiral stair. Originally published: London : British Broadcasting Corporation, 1979 - Mortimer and the sword Excalibur. Originally published: London : British Broadcasting Corporation, 1979.
OBNB doesn't sell books, but you may be able to find a copy at one of these websites:
Arabel and Mortimer by Joan Aiken. ISBN 0563177713. Published by British Broadcasting Corporation in 1980. Publication and catalogue information, links to buy online and reader comments.