What 'jammy' means in Royal Navy slang

'Jammy' is described as a Royal Navy-associated expression for someone who is improbably lucky. A family tradition held that relatives learned it in naval service, and a surviving example appears in a letter between two great-aunts from the 1920s. Its exclusively naval origin remains uncertain because it may have circulated more widely in Britain. The playground analogy sharpens the meaning: someone acts with poor motives, escapes the consequences, and receives an unexpected reward through sheer luck. The term frames Challenger's practical survey, which achieved far more than its planners could have expected.