Could you perhaps provide a source from where you heard this? Based on what reports dispatches Lord Wavell and even General Percival has submitted there is no singling out of the Australians as the cause for the Fall of Singapore.

Wavell's dispatch regarding his time as C-in-C of ABDA Command in the South West Pacific from January to February 1942 was published in 1946. This dispatch is considered by the British and the Dominion governments as the official military narrative of events regarding the theater as they are the formal conclusions of the formation commander. In Wavell's report, he noted the "Paucity of Allied Resources" in the region that limited the extent of operations his command could undertake and highlights its resemblance to the Greek Campaign. He goes on to state as a post-campaign evaluation that reinforcements of air and land forces was insufficient, operations in jungle climate required specialized training which was lacking and that air forces had inadequate ground organisation. According to his dispatch, upon taking Command he flew into Singapore on the 7th of January to assess the situation. At this point the III Indian Corps had just been defeated at the Battle of the Slim River and were fighting North of Kuala Lumpur. Wavell noted that III Indian Corps being constant engaged and on the retreat for the past month had resulted in significant deterioration of its fighting capacity and planned for its withdrawal to behind the Australian 8th Division in Johor to refit and regroup. They were to conduct demolitions and delays while withdrawing to Johor while the 8th Australian Division took up position at Muar to form a defensive line that III Indian Corps could withdraw behind. The 8th Australian Division was to be reinforced by the 45th Indian Infantry Brigade at Muar which had just arrived. Wavell's overall plan was to hold the line in Johor to build up adequate reinforcements and reorganize before launching a counter-attack. Wavell states in his dispatch that he was in-fact confident in the Australians to put up a good fight against the Japanese which they did at the Battles of Gemas and Muar.

Wavell did note that the Australian forces were small, with one brigade group still stationed in the Mersing area it would leave only one brigade to hold the line in the Muar area with the 45th Indian Infantry Brigade. Wavell believing that one Australian and one Indian Brigade would be able to halt the Japanese advance is questionable since the whole of III Indian Corps had failed to this. Regardless of the military validity behind planning to commit such as a small force, if anything it showed Wavell was supremely confident of the Australians considering that this dispatch was written in retrospect of the whole campaign. Follow the Commonwealth defeat at Muar, Wavell in fact assigned the blame for the loss to the 45th Indian Infantry Brigade as they were still raw and under trained. Following the withdrawal of Commonwealth forces to Singapore, Wavell had hoped to mount a prolonged resistance there with the forces available. He listed the 8th Australian Division which at this point had been reinforced by a Machine Gun Battalion as at good strength and committed them to the defense of the North West of Singapore. This signals that Wavell and Percival still had confidence in the Australian troops as they assigned them to defend the second most likely area for a Japanese attack while leaving the most likely area on the North East to the 18th Division because they were the freshest troops available. The remnants of III Indian Corps were left in reserve being the most exhausted and disorganized units. Thus, according to the actions of Wavell, it does not seem to indicate any blame or contempt towards the Australians during or immediately after the campaign.

Wavell proceeded to summarize the reasons for the Allies defeat in Southeast Asia and states that it was due to the Japanese moving too quickly which never gave the Allies a chance to reorganize and consolidate their forces for effective resistance. He highlights that the most important aspect of the Campaign was control of the air which the Allies failed to achieve. Wavell goes on to state that even with greater naval forces in the region than what was at the disposal of ABDA Command, the lack of air superiority would have prevented their effective use. Similarly, the states that the morale damage done by enemy air attacks on ground forces was also great. While Wavell's appreciation that the Japanese air forces were still weak compared to the Allies and that given sufficient reinforcements and time to reorganize the Allies could have wrestled control of the skies from them is very questionable. In relation to your question it clearly shows that Wavell blames, if anything in particular, the failure to win the air war in the region as the major reason for their subsequent defeat.

As this dispatch was about to be published in 1946, it was sent to the Australians for advance viewing and to see if they had any comments to add. The Australian government, in consultation with the military, made no comment and were satisfied with the report. There was some contention over Wavell's statement that the Australians were pressing for aircraft sent to reinforce ABDA be diverted to Australian defense, their reluctance to reinforce Timor and their denial of the request to reroute the 6th and 7th Australian divisions to Burma instead of back to Australia. Overall they did not see the need to issue a comment about any of these states as none of them were made by Wavell in an accusatory manner and their rationale behind all of these decisions had already been given previously by the Australian government. They also requested the input from Major-General C. A. Callaghan who was the AIF General Officer Command after Gordon Bennett left for Australia. Callaghan endorsed Wavell's dispatch as "fair and accurate" regarding the Australian involvement. He also further endorsed Percival's dispatch and even disavowed Bennett's account of the Malayan Campaign as inaccurate. Thus, the Australians issued no objection or showed any disapproval of these dispatches and no where in Wavell's dispatch does it lay any blame on the Australians for the loss of Singapore.

Hence, I don't really get where this conception of Wavell blaming the Australians for the Fall of Singapore might come from since it is not reflected in any formal capacity. The Australians overall were culpable to some extent like every other force that was defending Singapore. To say they were the main reason for the loss, however, would be inaccurate. As for scapegoats, the main person being scapegoated for the Fall of Singapore has been Percival since he was General Officer Commanding of Malaya Command. If you could provide me a source regarding the claim that Wavell blames the Australians for the Fall of Singapore, perhaps I could investigate it further since I would have a specific point to start from. However, from the official statements, Wavell clearly does not lay blame on Australia for the outcome of the campaign.

Sources:

Primary

WO 106/2556: General Wavell's despatch (Contains only Wavell's dispatch)

Series A816/1  Item 52/302/133A : Malaya and Singapore despatches. Lord Wavell and General Percival (Contains both dispatches and the deliberations by the Australian government)

Secondary

The Defence and Fall of Singapore by Brian Farrell