I need to find where to buy a rotary blade for my (15 years) old mower.
The mower is a:
20' Zephir Superfine (serial number 943H)
The manufacturer is (was?):
Greens Power Mowers- ABROATH Scotland UK

I look for a supplyer that would ship it to me to Portugal (or France)

Could it be that you mean Arbroath, Scotland?  (instead of Abroath)

Must be the home of lawn mowing from the hits on      arbroath lawn mowers

Like this one:

http://users.crocker.com/~jricci/currentmfg.html

There may be some standardization on mower blades, from my experience:
Length, bore of central hole, placement of hole(s) or whatever to
support the turning, or maybe on your mower blade this is unneccesary,
just the center bolt  holds the blade tight enoughg.
Ask around.

Good luck.

Did you find a blade for the Mower ?

Phil