> I'll believe that when I see it
You're seeing it right now, if you actually look.
"UK economy could be comparable to “Slovakia” in 10 years - says economist Duncan Weldon"
https://www.youtube.com/watch?v=R5g_S9BBtqw
> The UK, Germany and France are declining in lockstep,
Nope.
https://youtu.be/R5g_S9BBtqw?t=155
"Britain is unique among the G7 countries in that GDP per head is still below that when the pandemic hit."
Notice the "unique" bit.