In 1937, in an initially-unrelated development, the Australian Commonwealth Naval Board (ACNB)  approved the procurement of three net-laying boom defence vessels.
However, in February 1938, the ACNB also identified a need for a class of general purpose, 'local defence vessels' that were easy to construct and operate. (
This need emerged from plans for a training tender attached to the RAN anti-submarine warfare training school.)
The ships had to be capable of both anti-submarine and minesweeping duties.
Consequently, the number of Bar-class boom defence vessels ordered was reduced to two, and resources for the third were re-allocated to a prototype local defence vessel.

During July 1938, the RAN Director of Engineering, Rear Admiral P. E. McNeil, was instructed to develop plans for a local defence vessel, with a displacement of approximately 500 tons, a speed of at least 10 knots (19 km/h; 12 mph), and a range of 2,000 nautical miles (3,700 km; 2,300 mi).
McNeil completed his drawings in February 1939; his proposal called for a 680-ton vessel, with a speed of 15.5 knots (28.7 km/h; 17.8 mph), and a range of 2,850 nautical miles (5,280 km; 3,280 mi).
McNeil's unbuilt prototype – sometimes known as HMAS Kangaroo – more closely resembled a sloop than the original concept of a local defence vessel; the increase in size and speed also meant the vessel would have been more versatile than originally envisioned.
It would have been equipped with a 4-inch gun, ASDIC and either depth charge launchers or minesweeping equipment, depending on operational requirements.
 In the meantime, however, the order for three net-laying vessels was re-instated before construction of McNeil's prototype could begin. (
The second of these Bar-class boom vessels to be commissioned was instead named Kangaroo.)

Although McNeil's "Kangaroo class" was never built, his general concept attracted interest in Australian naval circles, as it offered advantages over existing minesweeper and anti-submarine classes and could be built in Australia with local resources, with the exception of weapons and some specialised instrumentation.
Although not perfectly suited for any specific role, the all-round general capability for minesweeping, anti-submarine warfare, patrol, and escort duties was seen as a good short-term solution until better vessels could be requisitioned or constructed.

In September 1939, following the outbreak of war, there was a new procurement process for seven ships of a design based on McNeil's concept.
Additional orders were soon placed by both the ACNB and the British Admiralty, and a total of 60 Bathurst-class ships were built, including 36 ordered by the RAN for home duties and 24 paid for by the Admiralty.
Of these British-ordered vessels, 20 vessels were commissioned into the RAN and crewed by Australian personnel, on the understanding that they would be attached to Royal Navy fleets; a further four vessels were commissioned into  the Royal Indian Navy.

The Bathurst class were officially classified as "Australian Minesweepers" (AMS) to hide their intended primary role in anti-submarine duties.
although the Bathursts were popularly referred to as corvettes.
In 1937, in an initially-unrelated development, the Australian Commonwealth Naval Board (ACNB)  approved the procurement of three net-laying boom defence vessels. However, in February 1938, the ACNB also identified a need for a class of general purpose, 'local defence vessels' that were easy to construct and operate. (This need emerged from plans for a training tender attached to the RAN anti-submarine warfare training school.) The ships had to be capable of both anti-submarine and minesweeping duties. Consequently, the number of Bar-class boom defence vessels ordered was reduced to two, and resources for the third were re-allocated to a prototype local defence vessel.
During July 1938, the RAN Director of Engineering, Rear Admiral P. E. McNeil, was instructed to develop plans for a local defence vessel, with a displacement of approximately 500 tons, a speed of at least 10 knots (19 km/h; 12 mph), and a range of 2,000 nautical miles (3,700 km; 2,300 mi). McNeil completed his drawings in February 1939; his proposal called for a 680-ton vessel, with a speed of 15.5 knots (28.7 km/h; 17.8 mph), and a range of 2,850 nautical miles (5,280 km; 3,280 mi). McNeil's unbuilt prototype – sometimes known as HMAS Kangaroo – more closely resembled a sloop than the original concept of a local defence vessel; the increase in size and speed also meant the vessel would have been more versatile than originally envisioned. It would have been equipped with a 4-inch gun, ASDIC and either depth charge launchers or minesweeping equipment, depending on operational requirements.  In the meantime, however, the order for three net-laying vessels was re-instated before construction of McNeil's prototype could begin. (The second of these Bar-class boom vessels to be commissioned was instead named Kangaroo.)
Although McNeil's "Kangaroo class" was never built, his general concept attracted interest in Australian naval circles, as it offered advantages over existing minesweeper and anti-submarine classes and could be built in Australia with local resources, with the exception of weapons and some specialised instrumentation. Although not perfectly suited for any specific role, the all-round general capability for minesweeping, anti-submarine warfare, patrol, and escort duties was seen as a good short-term solution until better vessels could be requisitioned or constructed.
In September 1939, following the outbreak of war, there was a new procurement process for seven ships of a design based on McNeil's concept. Additional orders were soon placed by both the ACNB and the British Admiralty, and a total of 60 Bathurst-class ships were built, including 36 ordered by the RAN for home duties and 24 paid for by the Admiralty. Of these British-ordered vessels, 20 vessels were commissioned into the RAN and crewed by Australian personnel, on the understanding that they would be attached to Royal Navy fleets; a further four vessels were commissioned into  the Royal Indian Navy.
The Bathurst class were officially classified as "Australian Minesweepers" (AMS) to hide their intended primary role in anti-submarine duties. although the Bathursts were popularly referred to as corvettes.
Bathurst-class corvette