Tours for women, gays, the disabled, seniors, pilgrims, families, and students
Accessible tours for the handicapped in England
Tours aimed at families
LGBT tours of Great Britain
Spiritual journeys to the British Isles
England tours for mature travelers
Singles tours and other options and tips for solo travelers in the U.K.
Student and youth tours of England, Scotland, and Wales
Tours and advice for women traveling in Great Britain
Though rarely do they have U.K. offerings, Intrepid Travel is well worth checking out. it is one of only two only major tour outfits I know (along with G Adventures) of that makes a concerted effort to travel like real independent travelers—small groups (max of 12 people), staying in mom-and-pop accommodations and getting around by public transport rather than a big tour bus.
This fantastic Australian company marries an independent travel style with the expertise of truly knowledgeable guides and a focus on the cultural experience of travel.
Intrepid really does run a different breed of group tour. Let me put it this way: When my parents—who travel widely and on their own and normally would never have even considered taking a group tour—suddenly found themselves with airfare to Japan but no time to plan a trip, I suggested they try booking with Intrepid. They did—and they have raved about it every since. Nearly seven years later, they were still in touch with their guide via email.
The Queen doesn't need a passport. Since all British passports are issued "In the name of Her Majesty," the Queen can just vouch for herself—though her husband Philip, son Prince Charles, and everyone one else in the household do have passports.