MK have had that type of shutter in use for quite a while and because MK fittings get used quite a lot here in Ireland you'll see plenty of them around.
The old schuko outlets here were unshuttered (dating back to the 1930s in some cases) but the odd BS546 outlet that's survived would be almost always MK and almost always switched and shuttered although i have seen some very old 5A ones of an unknown brand that were unshuttered. I've never seen an old BS546 2-pin socket here.
If any system needed shutters it's BS546 15A a child could definitely insert a finger and touch a live part without the need for any tools.
