WW2 ROYAL AIR FORCE RAF SIREN MACHINE ???

NOT SURE WHAT THIS IS BUT WHEN I PLUGGED IT IN IT MADE A HELL OF A NOISE , JUMPED ALL AROUND THE KITCHEN AND NEARLY GAVE ME A HEART-ATTACK ! . THE RAF STORE MARKINGS OF 10 KB/115 COMES UNDER ; RADIO. RADAR , TELEPHONE AND TELEGRAPHIC EQUIPMENT. I HAVE REMOVED THE PLUG BUT BUYER BEWARE !
P&P = £6 UK