3. 1954
Doesn't she look happy? Here's the Queen and Prince Philip leaving an event during a visit to Australia in 1954.

Australia is a Commonwealth Realm, which means they accept the Queen as their monarch. In addition to the United Kingdom, there are 15 other Commonwealth Realms including Canada, New Zealand, Jamaica, The Bahamas, and more. 

It's common for the royal family to visit these places, so here the couple are on one of those trips.