Former "Triple Nine girls" (from left) Evelyn Wong, 71; Lilian Lee, 75; and Lorna Jenner, 70; as well as former police officer George Mathews, 65, at a bunker once known as the Combined Operations Room in Pearl's Hill Terrace in Chinatown. They are in what used to be the Radio Control Room, where all 999 calls in Singapore were once answered. The secret bunker is now open to the public for tours.

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'Secret' police bunker open to public for first time