I grew up in South London, and as a small boy in the 1950s I did find the fronts of the SUBs quite severe! But not as severe as the 2-HALs, though. Our train was invariably an EPB, which to me has a friendly face compared with the SUBs and 2-HALs. Sometimes while waiting for our train, a 2-HAL formation would pass through the station at speed on its way to Maidstone, which I found unnerving! Perhaps the EPBs look more friendly because they have smaller driver's windows with prominent rain strips - their "eyes" have proper "eyebrows", unlike the bare, somewhat "bulging", eyes of the SUBs.