Little update - no-one has refused my price increases which I have applied selectively over the last month so far.
Some examples. None have increased for 3/4 years.
£7 to £8 (Front of semi)
£8 to £10 (Front and side of semi) x 2
£10.00 to £12.00 (Front and side of semi)
£13.50 to £15.00 (small Semi) x 2
£13.00 to £15.00 (small Semi) x 2
£15.00 to £17.00 (semi)
£15.50 to £18.00 (semi)
£18.00 to £20.00 (detached)
£18.00 to £21.00 (detached)
£20.00 to £23.00 (detached)
£25.00 to £28.00 (detached)
£30.00 to £34.00 (detached plus conny)
£32.00 to £36.00 (detached plus conny)
£35.00 to £40.00 (large detached)
So all above 10% but less than 15%. Feels right to me.
For some reason I find it more difficult to do mentally when they are compact like I imagine them seeing my van draw up at 9.00 am, leave at noon and they work out I've earned at least three figures.