I just popped into the local store for caraccesories. I browsed through the their filter catalogue to see if my Magnum were listed. To my surprise it was! And I was even more surprised that both air and oil filter were in stock! They had the Italian TECNECO filters. Cheap too!
http://www.tecneco.com
Air filter:
Tecneco ar147a - NOK 49,- á pcs.
Oil filter:
Tecneco ol154 - NOK 39,- á pcs.
A total of NOK 137,- = £ 11.01
Not bad! The Magnum were pleased!