London's Transport Commissioner, Peter Hendy CBE said:
"With London's population forecast to grow by one million people in the next 20 years, it is essential that we continue to invest in making our network more reliable and that we enable the London and UK economy to grow and prosper in the years ahead."
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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.