v3.23.3
Significant Accounting Policies - Narrative (Details) - GBP (£)
12 Months Ended
Jun. 30, 2023
Jun. 30, 2022
Jun. 30, 2021
Jun. 30, 2020
Disclosure of changes in accounting estimates [line items]        
Net assets £ 571,300,000      
Net current assets 226,100,000      
Cash and cash equivalents 164,703,000 £ 162,806,000 £ 69,884,000 £ 101,327,000
Loans and borrowings 0 0    
Grant received £ 494,000 139,000 £ 228,000  
Downside scenario        
Disclosure of changes in accounting estimates [line items]        
Percentage increase (decrease) in revenue 23.00%      
Increase (decrease) in cash and cash equivalents £ 87,000,000      
Severe downside scenario        
Disclosure of changes in accounting estimates [line items]        
Percentage increase (decrease) in revenue 32.00%      
Increase (decrease) in cash and cash equivalents £ 146,000,000      
Revolving Credit Facility        
Disclosure of changes in accounting estimates [line items]        
Undrawn borrowing facilities 350,000,000      
Loans and borrowings 0 £ 0    
Revolving Credit Facility | Downside scenario        
Disclosure of changes in accounting estimates [line items]        
Loans and borrowings 0      
Revolving Credit Facility | Severe downside scenario        
Disclosure of changes in accounting estimates [line items]        
Loans and borrowings 0      
Lexicon | Minimum        
Disclosure of changes in accounting estimates [line items]        
Range of customer relationship values 400,000      
Lexicon | Maximum        
Disclosure of changes in accounting estimates [line items]        
Range of customer relationship values £ 1,900,000      
Lexicon | Customer attrition        
Disclosure of changes in accounting estimates [line items]        
Percentage of reasonably possible increase in actuarial assumption 5.00%      
Percentage of reasonably possible decrease in actuarial assumption 5.00%      
Lexicon | Discount rate, measurement input        
Disclosure of changes in accounting estimates [line items]        
Percentage of reasonably possible increase in actuarial assumption 2.50%      
Percentage of reasonably possible decrease in actuarial assumption 2.50%      
Mudbath & Co Pty Ltd | Minimum        
Disclosure of changes in accounting estimates [line items]        
Range of customer relationship values £ 200,000      
Mudbath & Co Pty Ltd | Maximum        
Disclosure of changes in accounting estimates [line items]        
Range of customer relationship values £ 900,000      
Mudbath & Co Pty Ltd | Customer attrition        
Disclosure of changes in accounting estimates [line items]        
Percentage of reasonably possible increase in actuarial assumption 5.00%      
Percentage of reasonably possible decrease in actuarial assumption 5.00%      
Mudbath & Co Pty Ltd | Discount rate, measurement input        
Disclosure of changes in accounting estimates [line items]        
Percentage of reasonably possible increase in actuarial assumption 2.50%      
Percentage of reasonably possible decrease in actuarial assumption 2.50%      
DEK Corporation Pty Ltd | Minimum        
Disclosure of changes in accounting estimates [line items]        
Range of customer relationship values £ 5,700,000      
DEK Corporation Pty Ltd | Historic benchmark of customer relationship value as a proportion of consideration transferred        
Disclosure of changes in accounting estimates [line items]        
Percentage of reasonably possible increase in actuarial assumption 5.00%      
Percentage of reasonably possible decrease in actuarial assumption 5.00%