Green’s Dictionary of Slang

1. (Aus.) excellent, admirable.

1914

Bulletin (Sydney) 20 Aug. Red Page/1: Uz fur the nights, there’s allez whips o’ fun / In ’ops wif righto heifers ut yer wing.

2. (Aus.) favoured, admired.

1910

Sun. Times (Perth) 26 June 2nd sect. 9/7: They Say [...] That a dashing dentist got home on a confiding tailor last week. That having told the latter he was ‘Right O’ with two panto girls he ordered and got a swagger suit. That Mr. Snip was introduced [...] and made welcome.