Annual and transition report of foreign private issuers pursuant to Section 13 or 15(d)

Business combination agreement - Fair value of deemed shares issued (Details)

v3.21.2
Business combination agreement - Fair value of deemed shares issued (Details)
 1 Months Ended 9 Months Ended 12 Months Ended
Sep. 03, 2021
USD ($)
shares
Sep. 30, 2021
USD ($)
$ / shares
shares
Sep. 30, 2019
USD ($)
Sep. 30, 2021
USD ($)
item
$ / shares
shares
Sep. 30, 2020
USD ($)
Sep. 02, 2021
$ / shares
Apr. 25, 2021
$ / shares
Sep. 30, 2020
€ / shares
Disclosure of detailed information about business combination [line items]                
Share Exchange Ratio | item       46.06        
Price per share | (per share)   $ 0.0001   $ 0.0001   $ 0.0001 $ 1 € 0.0001
Profit / (loss) for the year | $   $ 651,973 $ 1,037,565 $ (271,729,101) $ (568,319)      
Business Combination Agreement                
Disclosure of detailed information about business combination [line items]                
Number of ordinary shares agreed to subscribe 90,000,000              
Shares issued 90,000,000              
Arqit Limited                
Disclosure of detailed information about business combination [line items]                
Profit / (loss) for the year | $   $ 651,973            
Arqit Limited | Business Combination Agreement                
Disclosure of detailed information about business combination [line items]                
Share Exchange Ratio | item       46.06        
Number of shares issued as incentive   1,825,096   1,825,096        
Exchanged for shares in the Company in reverse acquisition 1,954,174              
Fair value of the shares issued | $ $ 223,517,945              
Number of deemed shares issued representing same percentage of equity interest acquired 485,326              
Centricus Acquisition Corp. | Business Combination Agreement                
Disclosure of detailed information about business combination [line items]                
Number of ordinary shares for each ordinary share held   1   1        
Number of warrants for each warrant held   1   1        
Number of shares purchased prior to merger   2,200,000   2,200,000        
Consideration for shares purchased prior to merger | $   $ 22,000,000   $ 22,000,000        
Centricus Acquisition Corp. | Subscription Agreements                
Disclosure of detailed information about business combination [line items]                
Number of ordinary shares agreed to subscribe       7,100,000        
Price per share | $ / shares   $ 10.00   $ 10.00        
Gross proceeds | $       $ 71,000,000        
Shares issued       7,100,000