How close did the UK actually come to introducing an exit tax in 2025?

According to multiple reports, the Treasury undertook detailed work on a 20% charge on unrealised gains for individuals leaving the UK and considered introducing it in the 2025 Autumn Statement.
Professional firms and policy institutes described the exit tax as an active proposal that was abandoned only days before the Budget due to concerns about capital flight and a ‘rush for the door’ among wealthier taxpayers.