Day Tours from London

It depends what exactly are you looking for.
I did "Windsor, Bath and Stonehenge" with Golden Tours, and although it was rushed, I was fairly pleased.

Viator is not actually a tour company that runs tours, it is a tour consolidator. If you sign up with them, do your due diligence.

London Walks also does day tours.

Where do you want to go?

Viator hires third party representatives. We would suggest Evan Evans day tours. We have done many of them. We will be going to England this August and will use them again.

Where are you wanting to go? Many great day trips can be done ON YOUR OWN via train or bus. We have used both Evans Evans and Golden Tours many, many years ago. Be aware that you may be on a multi-lingual tour where you have to listen to the guide repeat everything 3 or more times in different languages. You will also be spending ALOT of time on the bus. You will have little to no flexibility and very limited time at any one stopping place (unless they stop at a shopping place they 'recommend'- meaning they get a kickback).

We haven't use them, but I have good things about London Walks. If you don't want to do it on your own, I'd check them out first.

Oh I totally agree, tourists can see a lot on their own. My husband and I do more on our own than on tours. We plan Tube/trains to Bath, Oxford, Cambridge, York, etc. Yes, it can be a problem with some tours, that you are on the bus so long. That didn't happen to us when we did the Evan Evans day tour of London though. We did a day trip around Paris in a small van also.

Bath, Oxford, Cambridge, Windsor, Brighton, Salisbury, Canterbury are all easily accessed by trains from London.
I would only look at an organised bus trip if you wanted to combine a couple of these on the one day.

London Walks. I've only taken their city walks, but they were all excellent or better.

London Walks, I did their day trip to the Cotswolds, and it was great.

Bath you can do with a company or just get yourself there on the train easily.

Viator is a consolidator that sells other companies' trips.