Sacha wrote:

Is there any reason to think you're going to lose it? We sometimes get
older shrubs or trees growing through their pots and usually they just stay
put quite happily. Some grow right through the Mypex and into the earth
beneath the glasshouses!

Marvelous stuff! I think it looks happy. There's plenty of room for it
to stretch its roots, just some few under planting of spring flowers
and ground ivy. I think I'll just leave it like it is. Thanks Sacha.