What is the X in X-mas?
outer borough of London, on the southeastern perimeter of the metropolis. Most of the borough is part of the historic county of Kent, but its westernmost extensions belong historically to Surrey. The largest in area of the London boroughs, it was established in 1965 by the amalgamation of the former boroughs of Beckenham and Bromley and (in Kent) the urban districts of Orpington, Penge, and part of Chislehurst and Sidcup. The borough extends over such areas as (roughly from north to south) Mottingham, Sydenham (in part), Elmstead, Penge, Anerley, Chislehurst, Beckenham, Bromley, Elmers End, Shortlands, St. Paul's Cray, Bickley, Petts Wood, Southborough, St. Mary Cray, Kevingtown, Orpington, Hayes, West Wickham, Locksbottom, Keston, Farnborough, Chelsfield, Green Street Green, Pratt's Bottom, Leaves Green, Downe, Cudham, Biggin Hill, and Westerham Hill