Hundreds of scientists protested outside the Treasury to demand that research budgets are protected from Government cuts.
With the Government's Comprehensive Spending Review less than two weeks away, the lively protesters chanted and sang their message asking Chancellor George Osborne to Save British Science.
The rally was organised by the Science is Vital campaign and a number of speakers talked about the risk of a so-called brain drain if talent leaves Britain following cuts.
One song replaced the words to Bruce Channel's Hey! Baby with the message "Hey Osborne, we wanna know if you'll fund our work". A second used Pink Floyd's Another Brick In The Wall with the final call "Hey Osborne, leave our geeks alone" which even got applause from a solitary figure watching from inside the Treasury.
Despite the upbeat atmosphere, the message was serious with speakers warning that cuts could halt progress and lose Britain its place at the forefront of scientific research.
Science is Vital was created by Dr Jenny Rohn, a cell biologist at University College London, who told the gathering: "They really are thinking of dismantling UK science. It makes absolutely no sense. Science is a wonderful thing for society, we cure diseases, we build bridges, we make buildings, we send things into space, we do all these things that make our culture so great and Britain has punched above its weight."
Imran Khan, director of the Campaign for Science and Engineering the UK, said the UK was looking to make cuts in science while other countries were investing for the future.
"With the numbers being bandied about - and we've heard 20%, 30% cuts to science investment - we could be on the verge of a catastrophic collapse in our science and engineering base. And I'm not over-reacting here. By the time it's obvious to the Government what they have done, it will be too late."
Science is Vital has collected 24,000 signatures on its petition opposing funding cuts and the campaign is supported by famous names like astronomer Sir Patrick Moore and comedian Dara O'Briain, who has a degree in mathematical physics.
A spokesman for the Department for Business, Innovation and Skills said: "We cannot speculate on the spending review while the process continues. The Government recognises the key role research, technology and innovation will play in rebalancing the economy and wants science to emerge from these tough economic times to be strong, sustainable and effective. We are strongly committed to making the economic case for science. But public spending on science, just like everything else has to stand up to rigorous economic scrutiny. In these austere times, the public should expect nothing less."