The Carlton Grange Hotel was an upscale hotel in central London. It served as the Second Doctor's base of operations after he was exiled to Earth by the Time Lords, but before he regenerated into the Third Doctor.
The Doctor had a full suite at the establishment, and appeared to enjoy lounging around the pool area, reading in his room, and taking supper in the hotel's restaurant when not on a mission.
One of the Doctor's first "missions in exile" involved the hotel guests in the room next to him. "The Terrible Trio of Tearaways" were three young brothers who behaved more like a gang. They ran wild through the hotel, capturing the Doctor's attention. When he overheard their plans to go joy riding in a plane owned by their legal guardian, Harrington Fitz-Walker, he followed them to prevent them from coming to harm. Initially spurned for his troubles, the Doctor eventually gained their trust and discovered that Fitz-Walker was in fact a posh criminal trying to steal from a local nuclear plant. (COMIC: Action in Exile)
Living in such a recognisable location made finding the Doctor a relatively simple matter. Dr Rowan Cartright discovered the Doctor's whereabouts by reading the front page of the Daily Record. He then placed a call to the Carlton Grange to invite the Doctor to submit himself to physical examination as part of a study he was conducting. (COMIC: The Mark of Terror)
On another occasion, a secret society of criminals, perhaps related to the Mafia, abducted the Doctor from the pool area of the hotel. It was comparatively easy for them to land their helicopter on top of the Carlton Grange and whisk him away. (COMIC: The Brotherhood)
The British Ministry of Defence could easily summon him at the Grange Carlton, as they did when they called his room to request his assistance in investigating what turned out to be an SOS signal the Ministry had received from a passing Quotron space craft. (COMIC: U.F.O.)