Hi IDIYathome,
Our warehouse staff have advised that the diameter of the barrel is 18mm and the length of the barrel is 35mm, so an 18mm diameter hole to a minimum depth of perhaps 37mm (to allow for the thickness of the inset front plate) should be sufficient.
Thanks for using Screwfix Q&A. JT
Answered by: JTremain
Date published: 2020-08-10