Cavity wall Insulation

A friend of mine a lady lives in quite a cold house and asked about insulation for her walls and was told by a company the cavity is too wide to insulate.
Its and oldish house originally cottages prob about early 1900's
Its rendered on the outside so cant see the brick bonding (rat trap etc ), is there a maximum cavity width?
Tia

Its normally the cavity being too narrow (less than 45mm) that prevents filling. I have heard of CWI companies charging extra for a wide cavity.
How wide is this one?

Not sure without getting up in attic and looking there or put a drill through in a discrete spot.