TOPIC:

The Service Medal is awarded for a number of years of service, 12 or 10 and can be awarded for conspicuous service.

It was announced in the St John Ambulance Brigade General Regulations for 1895, paragraph 11:

By command of H.R.H. the Prince of Wales, Grand Prior of the Order, the Council of the Order of St. John of Jerusalem in England intimate that Her Majesty has been graciously pleased to authorise the issue of Service Medals to reward Distinguished Services and to encourage efficiency and long service in the various Departments of the Order.

Members of the Brigade who have performed distinguished services, or have served honourably and efficiently for a period of not less than fifteen consecutive years, will be eligible for this medal.

It was minted in 1899. According to a snippet of research I have, the first presentation of these Medals was by the Prince of Wales at Marlborough on 6 January 1900.

This from The Times, 9 Jan 1900.