Why Tempest was still too early for a firm verdict

How is the Tempest fighter programme assessed?

It was probably a good idea, but still too nascent to judge firmly while fifth-generation aircraft were only entering service.

Tempest may have been a sound idea, but the programme was still too immature for a firm verdict in 2021. It was being presented as a sixth-generation aircraft while Britain was still bringing fifth-generation capability into service. A judgment would have to wait for the design and programme to mature.