On a recent visit to the Grade II listed RAF Club at 128 Piccadilly I was at first intrigued by a pair of narrow vertical windows either side of the door. Here's one of them viewed from inside the reception area – it's slathered in layers of paint and, as such, no longer functional.

Viewed from the street, these little windows are very hard to notice being as they are hidden behind the pillars that flank the late Victorian doorway. My hunch is that they were used for communication and delivery of letters etc when the heavy main door was closed and would have provided a level of security, especially at night. Any other suggestions and explanations are most welcome.
In January 1922 the building opened its doors to RAF Club members. Here's one of the elegant cartouches on the staircase:

Squadron badges are displayed within frames around the walls of the rooms and corridors. Each squadron has a different pictoral motif and motto with more than a third depicted in Latin.

I mused what happened when a new squadron was created. A meeting would likely be arranged to decide on the company identity, so to speak. I'd love to have been a fly on the wall listening to them coming up with snappy ideas only to find that another squadron had got there first.
The tone and sentiment of these mottos varies greatly. Some are attacking, others are caring. Some squadrons sound reliable, others leave no prisoners. Many of them could be movie titles or power ballads by Celine or Whitney, or advertising slogans for household products or alcoholic beverages like vermouth. As regards who these mottos are aimed at, most are generic, some describe the actions of many as in we/our/us, but there are also a handful that are in the first person as in, I will do this/that.Here's a list, in no particular order, of the some of the mottos shown in English. Please excuse a random use of initial caps instead of ALL CAPS as depicted in the frames.
Do Right Fear NaughtI Will Defend the RightForemost in AttackStrong to ServeDanger is our OpportunitySwift to StrikeEnduranceSurely and QuicklySilently We ServeSteadfast in SupportTally HoWith Speed I StrikeDespite The ElementsWe Fight To RebuildStrike HardNever FailingBeware BewareWe AvengeWatching Ever FaithfulDirect To KillReady To MoveAchieve Your AimAvengeStrike Hard Strike SureConfound and DestroyWe Guide To StrikeThis Arm Shall Do ItTo Hold On HighFriendshipFangs of DeathGoing DownOn Wings Of FireWe Kill By NightSupporting Liberty and JusticeLet Us To The BattleFirst From The EyriesWe Learn By TeachingPanache and PrecisionEven BetterKnowledge SustainsLearn and LeadKnowledge Dispels FearStrike Hard and Strike FastReadyAnywhere Any Time