[2] Callaway appeared for Paddington in Sydney Grade Cricket in 1913–14, playing alongside Monty Noble.

Sydney Morning Herald went on a stream of praise for the hundred, calling it "a splendid innings, entirely free from blemish", and about the "crispness and strength of his driving", "straight bat" and "splendid judgment"[4] He scored 578 runs in the season for Paddington at an average of 41.28 and took three wickets.

Callaway made his first class debut aged 18 for New South Wales against Queensland at the SCG in February 1915.

His second fifty took 27 minutes and the hundred was reached with a "magnificent straight drive that landed on the pickets at the southern end".

Callaway completed his double century, in 206 minutes, just before lunch on the second day as NSW added 146 runs in the first session.

The Sydney Morning Herald praised the power of his strokeplay, gritty temperament and the ability to play a long innings.

This method, of course, imparts power to his strokes, though from the defense point of view, it appears to leave considerable openings".

The Sydney Cricket Ground had an outfield of thick grass which made it very difficult to score boundaries.

[17] Some sources, including the Sydney Morning Herald reports of the day, call Callaway the first batsman to score a double century on first class debut.