The maker's mark underneath a small watering-can, a 'cactus watering can', states that it's from Kennedy in Loosdrecht.
Amazingly, on the digitized archives of a local newspaper a photograph could be found of Mr Kennedy's copper-smithy, made in January 1954. The caption stated it is the coppersmith's shop of Mr. Kennedy housed in an old school in Nieuw-Loosdrecht.
Not sure who Mr Kennedy is or if he is even in the picture - the photographer will have stood on a workbench in one corner and instructed the boys to pose with their work. Some of the brightly polished products of the workshop strategically scattered around a workbench - and there on the workbench in front is standing the exact same watering can.
Of course unlikely to be this exact specimen, but it is one of the exact same pattern. And as this was not mass-manufacture, this particular 'cactusgietertje' with the flattened shape sitting on the table here today was very likely made around 1954 too.
These copper body with brass handle+spout watering cans came into fashion from, I think, the 1930s and were most common during the fifties and sixties in The Netherlands. Generally called 'cactus watering cans' (cactusgietertje) they also are found in e.g. Germany, but seem to be less common in most other countries.
It's nice to be able to 'place' an object and very neat indeed seeing it when new in the place where it was made with the people that made it :)