An accident happening to an employed earner in or about any premises at which he is for the time being employed for the purposes of his employer’s trade or business shall be taken to arise out of and in the course of his employment if it happens while he is taking steps, on an actual or supposed emergency at those premises, to rescue, succour or protect persons who are, or are thought to be or possibly to be, injured or imperilled, or to avert or minimise serious damage to property.