How do I get rid of red spider mites from window reveals. We do not have any plants that may attract them. Red brick facings on outside of house with cavity and blockwork internal construction, with plaster over.

Your question reads like they're on the outside. Any long lasting insecticide (not aerosols, you'll usually find good long lasting products in pump sprayers or concentrates to make a suspension in water) applied to the brick should get them under control. It may take several applications, spread out over a few weeks.