South West Trains are promising that commuter services will be "normal" in the morning, following hours of delays due to engineering work.
In a statement, the company said: "Safety is our absolute priority. We have no choice but to make sure these repairs are carried out before we can restore train services on these lines."
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A lamp in the tower which houses Big Ben is to be switched off for the first time in more than 70 years.
Sir Bruce entertained audiences for more than seven decades.
Work in the tower will also pause over the bank holiday weekend.