Thanks for commenting. Here are the photos:
http://img3.freeimagehosting.net/image.php?4a06497205.jpghttp://img3.freeimagehosting.net/image.php?178655f647.jpgI guess it is possible that the rust is from cavity wall ties. I'm not sure how to be sure? Out of curiosity (and fear!!) why might the problem be more serious?
I dont think it is practical to pull out the offending rusty fixings in favour of some treated ones as they're not easily accessible. But I agree it would be the best remedy. Do you know of a suitable zinc based primer product that I can purchase from a DIY store? I assume the PVA Building adhesive advice I have previously been given is poor?
How about one of these products?
1) Toolstation Industrial Primer 500ml White, described as "Rust inhibitive primer which is ideal for building up repaired surfaces to a smooth consistent finish."
2) Toolstation Cold Galvanising Spray 500ml, described as "Ideal for use in coating pipework and steel fabrications to reduce corrision."
Both can be found here:
http://www.toolstation.com/index.html?code=60070Thanks for your help. It is much appreciated