The British Official History of the War in the Mediterranean and Middle East considered Operation Brevity to be a failure. The Australian Official History, however, gives the operation more credit. Brevity had actually achieved a good bit, and the main problem was that the British commanders were not ready to take risks to hold the ground that they had taken. By 17 May 1941, the British still had Halfaya Pass. The cruiser tanks had withdrawn without being pressed, as they were timidly commanded. The Germans had moved back into Salum (Sollum) since the British had pulled back.
The Australian Official History looks at the comparative losses and thinks that the British and Australians did not do so badly. As for tanks, the Germans lost three and the British lost five. Rommel considered that Halfaya was a very important position, as it dominated both roads that ran east-west.
General Wavell wrote that the priority for the British forces should be to push the German and Italian forces to the west, beyond Tobruk. They needed to make airfields available to the west for RAF use. They needed to use the 7th Armoured Division and the 7th and 9th Australian Divisions. At another meeting, the opinion was given that all Australian forces in the Middle East needed to be consolidated.
Churchill also weighed in on the situation. He tended to speak without knowing the relevant facts. His immediate concern was quite predictable. He wanted to know when the tanks from the Tiger Convoy could be brought into action. The truth was that at this point, an attack on Crete from German forces in Greece was the next crisis. This was a crisis created by Churchill's decision to go into Greece with a strong force that would not be enough to prevail. All the heavy weapons taken into Greece were left on the shore and only men and small arms were removed by ship.
There was new concern that German aircraft might be involved in attacking Crete from airfields in Syria. There was going to be pressure to intervene in Syria with the 7th Australian Division. One positive point was that the Italian army in east Africa surrendered on 19 May. Another positive development was that the force sent to Habbiniya in Iraq was nearing the air base.
A more concerning development at Tobruk was that posts S8 and S9 had remained in Australian hands. There had been a mistaken message that post S8 had bee "retaken", when it had never been lost. The next step was going to be attacking the enemy force that had been holding ground since 1 May 1941. This is based on the account in Vol.III of the Australian Official History.