Get this TalkMobile SIM only deal @ OneStopPhoneShop
If your parents are anything like mine and really only use their mobiles in emergencies, this £1PM SIM only deal from OneStopPhoneShop might be ideal. For a monthly quid, you get 25 minutes and 50 texts.
Talkmobile uses the Vodafone network.
Free delivery.
(Thanks to snowshine at HUKD)