Security steel doors: recommendations (London)?

Do you have any recommendations for installers of security doors? I don’t mean wooden doors that can be kicked down with an axe, but proper security doors with a steel frame, of the kind that is common in many continental European countries.
The only ones I know of are:
www.kensingtonsecuritydoorsandwindows.co.uk/ , which are a supplier of www.torteroloere.it/index.php?lng=2

and steelsecuritydoors.co.uk/

These security doors can be ‘disguised’ to look as ordinary wooden doors, so they would not look out of context.

AFAIK Banham doors are expensive but are still mostly wood, and cannot compare with these.

Please note the question is NOT whether you think such a door is appropriate or overkill, but simply if you know of any installer.

Thanks!