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The Gregorian Calendar was proclaimed in 1582 by Pope Gregory XIII.
No century year is a leap year unless it is exactly divisible by 400, e.g. 1600, 2000.
A leap second has been added to the national time scale at midnight 31 December 1995. The "Greenwich" time signal to mark the transition between 1995 and 1996 will contain six short pips instead of the usual five before the start of the long pip which marks the hour. The decision to change the time was made by Paris's International Earth Rotation Services. The end 1995 leap second will be the 29th since Coordinated Universal Time began in 1972.