v3.24.1.1.u2
Pensions and other post-retirement benefits - Disclosure of actuarial assumptions (Details)
Mar. 31, 2024
Mar. 31, 2023
Mar. 31, 2022
UK | Pensions      
Disclosure of defined benefit plans [line items]      
Discount rate – past service 4.87% 4.80% 2.78%
Discount rate – future service 4.92% 4.80% 2.85%
Rate of increase in RPI – past service 3.05% 3.17% 3.60%
Rate of increase in RPI – future service 2.92% 3.07% 3.33%
Salary increases 3.10% 3.11% 3.47%
Assumed life expectations for a retiree age 65 today: Males 21 years 6 months 21 years 10 months 24 days 22 years
Assumed life expectations for a retiree age 65 today: Females 23 years 6 months 23 years 8 months 12 days 23 years 9 months 18 days
Assumed life expectations for a retiree age 65 today: In 20 years: Males 22 years 7 months 6 days 23 years 23 years 2 months 12 days
Assumed life expectations for a retiree age 65 today: In 20 years: Females 24 years 10 months 24 days 25 years 1 month 6 days 25 years 2 months 12 days
UK | Pensions | Active members      
Disclosure of defined benefit plans [line items]      
Defined benefit obligation, member concentration percentage 14.00% 14.00%  
UK | Pensions | Deferred members      
Disclosure of defined benefit plans [line items]      
Defined benefit obligation, member concentration percentage 8.00% 9.00%  
UK | Pensions | Pensioner members      
Disclosure of defined benefit plans [line items]      
Defined benefit obligation, member concentration percentage 78.00% 77.00%  
US | Pensions      
Disclosure of defined benefit plans [line items]      
Discount rate – past service 5.15% 4.85% 3.65%
Discount rate – future service 5.15% 4.85% 3.65%
Salary increases 4.50% 4.50% 4.60%
Assumed life expectations for a retiree age 65 today: Males 21 years 7 months 6 days 21 years 7 months 6 days 21 years 4 months 24 days
Assumed life expectations for a retiree age 65 today: Females 23 years 10 months 24 days 23 years 9 months 18 days 23 years 7 months 6 days
Assumed life expectations for a retiree age 65 today: In 20 years: Males 23 years 3 months 18 days 23 years 2 months 12 days 23 years 1 month 6 days
Assumed life expectations for a retiree age 65 today: In 20 years: Females 25 years 6 months 25 years 4 months 24 days 25 years 3 months 18 days
US | Pensions | Active members      
Disclosure of defined benefit plans [line items]      
Defined benefit obligation, member concentration percentage 37.00% 37.00%  
US | Pensions | Deferred members      
Disclosure of defined benefit plans [line items]      
Defined benefit obligation, member concentration percentage 10.00% 9.00%  
US | Pensions | Pensioner members      
Disclosure of defined benefit plans [line items]      
Defined benefit obligation, member concentration percentage 53.00% 54.00%  
US | Other post-retirement benefits      
Disclosure of defined benefit plans [line items]      
Discount rate – past service 5.15% 4.85% 3.65%
Discount rate – future service 5.15% 4.85% 3.65%
Salary increases 4.50% 4.50% 4.60%
Initial healthcare cost trend rate 7.10% 6.80% 6.80%
Ultimate healthcare cost trend rate 4.50% 4.50% 4.50%
US | Other post-retirement benefits | Active members      
Disclosure of defined benefit plans [line items]      
Defined benefit obligation, member concentration percentage 29.00% 33.00%  
US | Other post-retirement benefits | Pensioner members      
Disclosure of defined benefit plans [line items]      
Defined benefit obligation, member concentration percentage 71.00% 67.00%