Amazon AU has the 6 x Inspector Allan Grant series in an omnibus edition for $1.99:
1. The Man in the Queue
2. A Shilling for Candles
3. The Franchise Affair
4. To Love and Be Wise
5. The Daughter of Time
6. The Singing Sands
https://www.amazon.com.au/INSPECTOR-...icia+wentworth
blurb:
Spoiler:
This volume contains six mystery novels by amazing British writer Elizabeth Mackintosh, who wrote under the pen names "Josephine Tey" and "Gordon Daviot"
In five of the novels the hero is Scotland Yard Inspector Alan Grant. (Grant appears in a sixth, The Franchise Affair, as a minor character.)
The most famous of these is The Daughter of Time, in which Grant, laid up in hospital, has friends research reference books and contemporary documents so that he can puzzle out the mystery of whether King Richard III of England murdered his nephews, the Princes in the Tower. Grant comes to the firm conclusion that King Richard was totally innocent of the death of the Princes.
In 1990, this novel was selected by the British-based Crime Writers' Association as the greatest mystery novel of all time.
The Franchise Affair, also included in this collection, was 11th on the same list. Although set in the 1940s, it is based on the 18th-century case of Elizabeth Canning.
The Singing Sands, last of the books in this collection, was found in her papers after her death, and published posthumously.
Edit
Kobo AU has the individual Allan Grant novels for 99c, and other Tey for $1.02.