Thanks to Stan0101 for this five star review on TripAdvisor…
I've taken about 8 different walks with London Walks and all have had very knowledgeable guides who knew how to handle the size of the group (ranging from 6 to 30 the times I've gone). Many of the guides have been doing this type of work with London Walks for 20 or more years. London Walks offers dozens of tours each week including some day trips to places like Oxford and Canterbury as well as many different neighborhoods around the city such as Hampstead, Little Venice, and Marylebone. There is history all over London so getting out of the city center adds to depth of understanding. The guide at the National Gallery (Margaret) gave one of the best art museum tours I've ever had with interesting details about the technique and history of the noteworthy paintings the tour focused on. You can buy a discount card which gets you 2 pounds off any tours after the first bringing the price down to 8 pounds which is a great bargain for a quality tour.
A London Walk costs £10 – £8 concession. To join a London Walk, simply meet your guide at the designated tube station at the appointed time. Details of all London Walks can be found at www.walks.com.