A major report says that the main losers of Brexit among EU stakeholders are those that promote less regulatory burden for EU businesses and stronger protection of copyright.
It also says that Brexit would also push the remaining EU governments to pay more to the EU.
The report, published on Tuesday, comes in the wake of the official launch at the weekend of the campaign on Britain's referendum on its membership of the EU.
Opinion polls show that the outcome of the poll on 23 June is still too close to call.
The Vote Watch Europe report studies the possible effects of Brexit, saying that its findings show that the dynamics in the EU institutions would change "substantially" if the UK left the EU.
It concludes, "Most of the British politicians who play a direct role in the EU institutions are favourable to free market policies.
"In the Council there are David Cameron's Conservative ministers. In the European Parliament, most of the British MEPs are on the centre-right side of the political spectrum (Conservatives in the ECR group, and UKIP in the EFDD group), while the Labour MEPs are much less prone to support extensive regulation than their Socialist colleagues from other countries, for example France."
The report's authors, including Simon Hix of the LSE, say a Brexit would create "more regulatory burden on EU businesses and weaker copyright protection in the EU.
Another effect, it says, is that the EU budget as a whole would be smaller, while member states' contributions would increase.
It predicts there would also be a "stronger push for tax harmonisation and higher taxation of financial transactions.
One other likely spin off is that there would be less support for the nuclear industry and exploitation of unconventional energy sources, for example, shale gas.
The report also makes a detailed analysis of the UK's voting record in the Council and European Parliament.
On this, some of the key points are that:
- The UK is the most outvoted member state in the EU Council. However, it has supported more than 97 per cent of the EU laws adopted in the last 12 years;
- The UK government was on the losing side a far higher proportion of times than any other EU government in the 2009-15 period: jumping from being on the minority (losing) side only 2.6 per cent of the time in 2004-09 to being on the minority (losing) side 12.3 per cent of the time in the 2009-15 period.
Vote Watch says that British opposition to EU policies occurred especially on budget, foreign policy and foreign aid issues.
Nevertheless, the UK was not the most "oppositional" government on several important issue areas, including internal market, legal affairs, transport, environment, and fisheries.
It notes that Sweden, the Netherlands and Denmark are the UK's closest allies in the EU Council and would lose an important partner if Brexit occurred.
According to its analysis, the UK has diminished its influence in the European Parliament in recent years, as a result of "self-distancing" of some of its own party delegations from the EU's mainstream political families, as well as due to the results of the latest EU elections in the UK.
"Nevertheless, UK MEPs have captured many powerful agenda-setting positions, such as rapporteurships of key EU legislation and committee chairmanships," it points out.
British MEPs, states the report, have held several 'top offices' in Parliament since 2004.
Two have been Vice-Presidents (Edward McMillan-Scott and Diana Wallis), three have been quaestors (Jim Nicholson, Bill Newton-Dunn, and Catherine Bearder), four have been political group leaders (Graham Watson, Martin Callanan, Nigel Farage, and Syed Kamall), and 10 have been committees chairs (Giles Chichester, Phillip Whitehead, Arlene McCarthy, Neil Parish, Sharon Bowles, Malcolm Harbour, Brian Simpson, Claude Moraes, Vicky Ford, and Linda McAvan).
In addition, a British MEP has chaired the powerful internal market committee continuously since 2004, and in the current Parliament, British MEPs chair three key committees: internal market and consumer protection (Vicky Ford), civil liberties and justice and home affairs (Claude Moraes), and international development (Linda McAvan).
The report also compares British participation in Parliament with other member states.
It says, "One way of assessing this is to compare the percentage of MEPs each member state had in each two-and-a-half year period (2004-06, 2007-09, 2009-11, 2012-14, 2014-16) with the percentage of top offices their MEPs held."
In general, since 2004, when compared to all member states, the UK has been slightly 'over-represented', in that there have been a larger proportion of British MEPs in top offices than British MEPs as a proportion of all MEPs.
Nevertheless, all larger member states win more top offices than smaller member states, even relative to their number of MEPs, and the largest member state (Germany) does particularly well.
"This," says the report, "is because when a political group wins a top office, this office almost always goes to an MEP from a larger party delegation within the group, which is usually a party from one of the larger member states.
"So, the fairest comparison is between the larger member states. Compared to the other larger member states, the UK is slightly 'under-represented' in the top offices in the Parliament."
The UK won more top offices than most other large member states in 2009-11, but fewer top offices than the other larger member states in every other period since 2004.
Reaction to the report was swift, with UKIP's trade spokesperson and deputy Chair William Dartmouth telling this website, "This report demonstrates that Britain in the EU really is like a square peg in a round hole. We are by a country mile the most outvoted state at the European Council and in the European Parliament.
"In the EU, the British government has consistently failed to protect our national interests. We are better off outside the EU when we can take back more control of the laws which affect our businesses and lives. The UK has one Commissioner out of 28, that fact and the consistent losses at the European Council shows the UK has no meaningful influence in the EU."