He insisted his exit was 'totally amicable'. In an email to associates obtained by PRWeek, he said: 'I quickly realised that PA in the public sector is a much more "back office" function than I was used to.'
Walkington was the Liberal Democrats' director of comms for the last general election, and previously PA director at BT and Texaco.
A TfL spokesman said it had not decided on whether to replace Walkington.
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