Since she is flying 'A' flag she must be on trials and not yet handed over so her 'house-flag' would be that of her builders, John Brown, which was white with a red saltire and the initials J, B, Co, Ltd in the quarters.
Thanks we live and learn would this also preclude the flying of an ensign which I can't see in the photo. As a matter of interest I sailed on her predecssor the 1915 Northumberland. 4 sticks and an open wheel house with a vast number of toilets situated in the most unexpected places
Somewhat remiss of them not to be flying an ensign, I agree. If flown it would have been from a gaff on the mainmast about where the top of the posts are but there doesn't even seem to be a saving blur on the photo that we might construe as an ensign. I always thought her one of Federal's best looking ships, although the entire fleet - almost - would be candidates.
This "Northumberland" had the distinction of being the first overseas ship to berth on the newly built Island Harbour in Bluff, although on opening day it was the "New Zealand Star" that berthed and gets the credit. When "Northumberland" berthed the Island Harbour was still under construction and she was using it as a lay-by berth. If I remember rightly the first trading ship ever to berth at the Island Harbour was the "Navua" sometime in 1962.
It was originally intended that the "Northumberland" would be the NZSCo's fourth "Turakina" but instead she took her present name.
Interesting to note that the "Northumberland" made her maiden voyage out to Australia in May 1955 but it was not until 1958 that she first visited New Zealand.