To give you some context, we booked this tour for 7 people, including 4 adults and 3 'kids' aged 10, 12, and 15. We were staying in a Central London hotel and had the tour start time changed to 8 am as suggested by the tour operator. Our tour took place beginning of July when temperatures in London and surrounding areas was near 90 degrees. We have booked multiple Viator tours, including another on this same trip which have been excellent. This, though left me flabbergasted.
On the plus side was Stonehenge itself, the convenience of hotel pick-up, and of course the efficiency a private car offers in terms of not having to wait for a tour bus full of people. This is where the stuff on the plus side ends. First, the van - a Mercedes van with two rows of seats facing each other - was a tight squeeze for us. We are by no means big people with the tallest in our group being 5'10''. One adult sat up front and the remaining three kids and three adults in the back and we sat like sardines in the back with no space to move our legs. I can't even imagine how 8 people which is the max size allowed for this tour would fit in that van. Also, if you have people who are prone to car sickness as we did you may find that the rear facing seats are less than ideal.
While we enjoyed our time at Stonehenge, our return trip to London was absolutely miserable given that the AC was not operational and it was a sweltering 2 hour drive back in 90 degree weather. Those of us sitting in the back didnt even have the benefit of air circulation from the windows! To make matters worst our driver - while very nice - was useless in offering any solutions or a reprieve. In fact to make matters worst he told us that he noticed the air conditioning wasnt working before he picked us up! Unfortunately this tour offered no value for the price charged. The ride in the big tour bus - which was a fraction of the cost - would have likely been more comfortable!! In fact, you may find booking a taxi and purchase of Stonehenge tickets 50 pounds for 2 adults 2 children on site to be more cost efficient, hence making this a waste of money.
I can only hope that this is resolved for future tours though In the meanwhile consider yourself warned!