Why is it normal in British English to say map room (for a room for keeping and viewing maps in) but games room (for a room for playing games in)?
To my native British ear these forms sound overwhelmingly preferable, even if the alternative forms are also sometimes used. Websearches yielded the following data.
Sites on the .uk domain:
"map room" 23800 hits "maps room" 17400 hits "game room" 407,000 hits "games room" 803,000 hits
Some of the hits for "maps room" were misleading, so I narrowed to the .ac.uk domain and got
"map room" 1870 hits "maps room" 43 hits "game room" 359 hits "games room" 2320 hits
which supports what my ears are telling me.
(A worldwide search yielded
"map room" 606000 hits "maps room" 196000 hits "game room" 38,700,000 hits "games room" 10,700,000 hits
Clearly in non-British English game room is common, but the question concerns British English only.)
I am wondering whether the impression one gets from the notion of a room for reading maps in tends to be of maps that are either all similar in form or, even if some aren't, are nonetheless essentially similar to each other; whereas, when the notion is of a room for playing games in, one is more likely to get an impression of significant variation. Moreover, a map in this connection is thought of as stored and fixed, whereas although the tools for a game can be stored in a room, the term "game" can also denote an instance of playing the game, and in this sense a new game is created each time the game is played, with great variety as a consequence. There is perhaps more perceived variety in playing than in consulting.
And what, in British English that does not grate on native ears, should we call a room that is both for reading maps in and for playing games in? A map and games room? Although that sounds right to my ear, doubt arises when I start thinking about it. Do people have some other suggestions?