This comes from the BBC's Welsh timeline, which was refering to the Norman invasion of Wales, AFTER the 1066 invasion of England.
The Wikinerds/Nerdshift (NOT Wikipedia) error was editing "Wales" to read "Britain". SLOPPY!
A lot more of their article was a jumbled mess, too.
If you use their 'external link' to the BBC's Timeline, there is a lot worth looking at, if Welsh history is an interest.
I don't know how soon after 1066 the first Norman incursion into Wales was, but the final conquest of Wales wasn't until much later, 1276-1284, under King Edward I, although Henry II (1154-1189) had nominally subjugated the country.