For all tours booked for the future, the limit on group size is:
For continental Europe: 6
For the UK and Ireland: 7
This helps me to contain all tours to those with me at the wheel 100% of the time without need for an extra driver. In the past I have done tours for larger groups but that was when I was married and my now ex-wife was a part of the business. Now that I am a solo act, I prefer to keep it simple.