Knowing which is the best radiator paint depends on the type of finish required. For a gloss finish, consider Dulux Trade Quick Dry Gloss or Dulux Trade High Gloss. For an eggshell finish, consider Dulux Trade Eggshell or for a flatter, more matt-like finish consider Dulux Trade Satinwood or Dulux Trade Quick Dry Satinwood.
Ronseal also produce a specific radiator paint, Ronseal Stays White Radiator Paint or in a handy aerosol can for ease of application: Ronseal Quick Drying Radiator Paint.
Alternatively, Crown Paints. For a gloss finish, consider Crown Quick Dry Gloss. For a satin finish, try Crown Non Drip Satin or Crown Solo One Coat Satin.