As has been documented before on Stampboards, this seller Michael Hudson owner of sydneystampcentre has a habit of buying plain (no cachet) FDCs, printing a suitable picture on them, and then listing them on ebay.
While such a practice is apparently acceptable in the USA, it is 100% frowned upon, to say the least, in Australia.
Especially if you "accidentally" forget to declare the modern addition.
Unfortunately, there has been a slight outbreak of fail on this cover:
As he has chosen to illustrate Australia's nursing tradition with a picture of the actresses Hattie Jacques and Joan Hickson, taken from the British comedy film "Carry on Nurse", which came out in 1959, 4 years after the stamp was issued.
The original picture he has used is here:
He has 2 other 1955 Nurse covers for sale at the minute. Both with recent additions, no doubt images from the web.