did any extension take place between the year 1901-1907?
Yes extension to Euston, although the C&BR proposals were never implemented, the Euston extension was quickly built and opened on 12 May 1907
City and South London Railway
 Although the C&BR proposals were never implemented, the Euston extension was quickly built and opened on 12 May 1907, with stations at:
what is the city and south london railway? The first deep-level underground "tube" railway in the world when was it built? UNANSWERABLE who designed it? Mather & Platt where did this tube start from? City of London who were the original inhabitants of this city? Natives of Britannia, continental Europe, the Middle East, and North Africa. what is the motto of this city? The Latin motto of the City is ""Domine dirige nos"", which translates as "Lord, direct us" are there any libraries here? Yes, Guildhall Library, and City Business Library where does the tube connect to from this city? Stockwell
wiki:20646431
City and South London Railway [SEP] Extension to Euston, 1901–1907
A third pair of tunnels would be constructed under the Thames to connect with the original abandoned tunnels north of Borough station and then the C&BR route would be constructed as previously approved with connections to the existing C&SLR route at London Bridge and Oval. This time, the bill was approved and received royal assent as the "City and South London Railway Act, 1903" on 11 August 1903. Although the C&BR proposals were never implemented, the Euston extension was quickly built and opened on 12 May 1907, with stations at: