suitability for beads in cavity.

[TheMitchells]

I have seen here posts about blown beads being pumped into cavity walls under pressure but am unable to find it again😒.  A friend has been renovating an old stone cottage and seemed to think that he could not use cavity wall insulation as the walls were uneven and beads would not fill the space.  But I am sure i saw something on here about them being blown in with 100psi which may work.  Does anyone have any recommendations for companies that may be able to help? We are on Oxfordshire/Northants border.  or point me to the post.....  thanks, in advance.