A major lobby group just unveiled a list of needed 'revolutionary' reforms to stop Britain leaving the EU

Britain's Prime Minister is under a serious amount of pressure to secure the renegotiation of the country's membership within the European Union - and if he doesn't, the nation could leave the EU, says financial and related professional services lobby group TheCityUK.

Britain's ruling Conservative Party is delivering a referendum by 2017 over whether Britain will stay part of the EU or not.

The Tories are largely against leaving the EU and UK Chancellor George Osborne has explicitly said that he would prefer to stay within the EU and negotiate "a better deal."

Cameron told EU leaders last week that Britain could easily leave the EU if it doesn't hash out a renegotiation. Meanwhile prominent members of the business community in Britain published a 1,000 page study, entitled "Change, or Go," that implicitly said Cameron has to secure some "major reforms" to "introduce mechanisms to reduce the burden of regulation on businesses" or face a Brexit.

TheCityUK's report today supports the same idea - reform Britain's EU membership and get us a better deal or deal with the nation leaving the EU for good.

TheCityUK made a series of 25 recommendations in a report, sent to Business Insider, on what Cameron should ask for when speaking to the EU. The group insisted in the report that "the reforms which are needed are numerous but are in many cases modest rather than revolutionary. It is through these numerous but necessary small reforms that real change will be achieved."

It emphasised that the reforms are not about "more Europe" or "less Europe", but about creating a "better, more thoughtful Europe".

"Fact not fiction should inform the EU reform agenda. The evidence we've gathered from the financial and related professional services industry shows that continued membership of the EU is vital for UK competitiveness, but a lot needs to change if the EU is to better serve the interests of its 500 million people," said Sir Gerry Grimstone, Chairman, TheCityUK.

"The City is Europe's financial capital and our members, representing many different countries, want practical change that can be delivered quickly, promote economic growth, bolster global trade and investment, and secure Europe's competitive position in the world. Let's get on with it."

"We firmly believe that the EU can work more efficiently and the UK is not alone in calling for its reform; other Member States have also put forward ambitious proposals. However, to achieve the goals that we have outlined, real progress and commitments to reform need to be made by all players involved from across the private and public sectors."

The 25 recommendations fall across four main categories:

• A deep and strong Single Market, open to the world
• Better regulation
• A European agenda for jobs, growth and competitiveness
• Fair and equal treatment of all Member States

Here is the list in the report: