Thank you @riverrun I will have a look. I have some Vintage PAL injector blades, however, I need something to compare them with.Chinese Schick blades are available from Amazon US:
They charge you the correct amount of VAT, so no Royal Mail penalty to be paid on arrival.
Two times 4 packs of 7 blades give a reasonable total price. They are very good blades.
Personna blades are good if you can stand the dreadful plastic container.
You can't safely fit a blade without a key. If you get some Chinese Schicks from the US you will get good metal containers that can be used to transfer other blades into the razor. It's quite simple. Then you can get cheap Proline blades and use those.