"her school, with its alien house system, might have been in Ealing"
Hawtrey House, Eton College (near Windsor)
Creative Commons AttributionHawtrey House, Eton College (near Windsor) - Credit: Elliott Brown, Flickr

 Ealing is a suburb of west London.

Muriel Spark is making the point that during the 20th century some features of the secondary educational system were common to schools throughout Britain. Several of these  aspects, such as  the system of 'houses', were based on the practices of the public school system. In the public school system, 'houses' were residential units whilst in the non-boarding state and independent sector they were simply a means of dividing pupils into groups for competitive purposes. The 'house' system is still in use in many British schools today.

The eduational system in Scotland has since followed a different course from that of England, Wales and Northern Ireland.