The two most plausible possibilities: (1) independent invention, or (2) there was lots of Punic maritime trade with the British Isles for an extended period and the technique (or even the actual goods) could have arrived that way. Main of the toponyms in the British Isles are Punic in origin. https://dispatchesfromturtleisland.blogspot.com/2016/12/phoenicianpunic-names-in-britain-and.html
"MANY of main toponyms . . . "
Another possibility is that thread-splicing didn't emerge in Egypt, like the wheel probably didn't originate in Mespotamia. Trade, most definitely.