According to the RHS website, Holly could well be our culprit for the invasive roots! I won’t be sad to cut it down if I am honest. It’s a menace.

And Holly has roots which go down as far as 25, yes 25 metres in search of moisture! It’s a good partner to mares tail which also has extremely long stretching roots! Ok tomorrow morning I will get out a hacksaw! Holly begone!

It’s true my husband thinks the Phormium might be to blame but we have one monster in the bed beside the drive. I think it will be easier to move a smaller one for sure but the big one needs a bit of tlc.

I know one of the plant websites (crocus.com?) shows silhouettes of plants and roots. I shall investigate further!