Adaptimmune Annual report [Section 13 and 15(d), not S-K Item 405]

Share-based compensation - Option Plans (Details)

Share-based compensation - Option Plans (Details)																12 Months Ended
Share-based compensation - Option Plans (Details)	Jul. 01, 2024	Jan. 15, 2024	Nov. 01, 2023	Jul. 03, 2023	Jul. 01, 2022	Jul. 01, 2021	Jul. 01, 2020	Jul. 02, 2019	Jul. 05, 2018	Jun. 22, 2018	Jul. 03, 2017	Nov. 28, 2016	Aug. 11, 2016	Jun. 23, 2016	Mar. 16, 2015 GBP (£) item	Dec. 31, 2024 shares
Share based compensation
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period																10 years
Number of option schemes \| item															3
Restricted Stock Units (RSUs) [Member]
Share based compensation
Exercise price \| shares																0.001
Vesting percentage (as a percent)																25.00%
Vesting period (in years)																4 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period															10 years
Scheme limit, grants as a percentage of fully diluted share capital of the Company immediately following the IPO (as a percent)															8.00%
Scheme limit, automatic increase percentage (as a percent)															4.00%
Options granted in January 2016 and March 2015
Share based compensation
Maximum value of option grants per participant \| £															£ 60,000
Options granted on December 31, 2023 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)																25.00%
Options granted on December 31, 2023 \| Share-Based Payment Arrangement, Tranche Three [Member]
Share based compensation
Vesting percentage (as a percent)																75.00%
Vesting period (in years)																3 years
Non-executive director \| Options granted on June 23, 2016 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)														25.00%
Vesting period (in years)														1 year
Non-executive director \| Options granted on June 23, 2016 \| Monthly installments over the following two years
Share based compensation
Vesting percentage (as a percent)														75.00%
Vesting period (in years)														2 years
Non-executive director \| Options granted on August 11, 2016 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)													100.00%
Vesting period (in years)													1 year
Non-executive director \| Options granted on November 28, 2016 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)												25.00%
Vesting period (in years)												1 year
Non-executive director \| Options granted on November 28, 2016 \| Monthly installments over the following two years
Share based compensation
Vesting percentage (as a percent)												75.00%
Vesting period (in years)												2 years
Non-executive director \| Options granted on July 3, 2017 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)											100.00%
Vesting period (in years)											1 year
Non-executive director \| Options granted on June 22, 2018 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)										100.00%
Vesting period (in years)										1 year
Non-executive director \| Options granted on July 5, 2018 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)									25.00%
Vesting period (in years)									1 year
Non-executive director \| Options granted on July 5, 2018 \| Monthly installments over the following two years
Share based compensation
Vesting percentage (as a percent)									75.00%
Vesting period (in years)									2 years
Non-executive director \| Options granted on July 2, 2019 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)								100.00%
Vesting period (in years)								1 year
Non-executive director \| Options granted on July 1, 2020 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)							100.00%
Vesting period (in years)							1 year
Non-executive director \| Options granted on July 1, 2021 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)						100.00%
Vesting period (in years)						1 year
Non-executive director \| Options granted on July 1, 2022 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)					100.00%
Vesting period (in years)					1 year
Non-executive director \| Options granted on July 3, 2023 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)				100.00%
Vesting period (in years)				1 year
Non-executive director \| Options granted on November 1, 2023 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)			25.00%
Vesting period (in years)			1 year
Non-executive director \| Options granted on November 1, 2023 \| Monthly installments over the following two years
Share based compensation
Vesting percentage (as a percent)			75.00%
Vesting period (in years)			2 years
Non-executive director \| Options granted on January 15, 2024 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)		100.00%
Vesting period (in years)		1 year
Non-executive director \| Options granted on July 1, 2024 \| Share-Based Payment Arrangement, Tranche One [Member]
Share based compensation
Vesting percentage (as a percent)	100.00%
Vesting period (in years)	1 year