The Gallipoli Star medal has an interesting and controversial background dating from during WW1. The medal was originally supported by General Birdwood (General Officer Commanding the ANZAC force at Gallipoli) and was designed was designed in 1917 by R K Peacock of the Australian Defence Department.
The award was discussed informally with the King of the Empire by General Birdwood, a popular Commander of the ANZAC force and was approved in-principle for issue by King George V in 1917. The British Parliament then (as a matter of protocol) had to formally recommend this award to the King. However, at the time the British members of parliament insisted that the entitlement for the issue of such an award should also be conferred to British forces that served at Gallipoli. Possibly a fair suggestion at the time, but the New Zealand and Australian Prime Ministers discussed the issue and strongly represented a view that a specific medal should be awarded for Australian / New Zealand commitment so early in WW1.
The Prime Ministers decided it would be a better situation not to have the award than to have it issued to all troops associated with the Gallipoli theatre of conflict as the Gallipoli Star was a medal especially designed for Australian and New Zealand military personnel that qualified for the award.