The Lightning overwing tanks could be jettisoned in flight - the pylons were fitted with explosive release units.
From AP101B-1003, 5 and 6-15A: Part 2: Chapter 1: Para 35
Overwing Tank Jettison:
35. Empty overwing tanks may be jettisoned between 200 and 250 knots and up to 0.75M at heights up to 40,000ft in straight and level flight. Overwing tanks containing fuel are not to be jettisoned.
From AP101B-1003, 5 and 6-15A: Part 2: Chapter 1: Para 35
Overwing Tank Jettison:
35. Empty overwing tanks may be jettisoned between 200 and 250 knots and up to 0.75M at heights up to 40,000ft in straight and level flight. Overwing tanks containing fuel are not to be jettisoned.