Prime Minister David Cameron kicked off the week repeating the main message of the "In" campaign: that European Union membership makes Britain stronger, safer and better off.
Boris Johnson, the main leader of the "Out" campaign, argued that membership of a project to create a European state would ultimately make Britain weaker and poorer.
"We are against the big battalions, the people ranged against us are very considerable and very powerful, we have the entire establishment against us," Johnson said during a trip on an Out campaign bus in Cornwall in southern England.
"It is a David versus Goliath scenario ... We are a small, plucky, hardy bunch of fighters but I think when you look at what happened in the David and Goliath struggle there is every reason to be optimistic."
Still, groups campaigning to take Britain out of the EU have raised more cash in recent weeks, securing 8.2 million pounds in the 12 weeks from Feb. 1, while the groups campaigning to keep Britain in the EU raised 7.5 million pounds.
Out and In battled with their strongest cards by the end of the week: immigration and the economy.
Out and eurosceptic newspapers made much of national insurance number figures which they said indicated a gulf between official numbers in immigration and the reality.
In campaigners purred when the Bank of England said Brexit could push the world's fifth largest economy into recession while the International Monetary Fund said it could start a spiral of weaker growth and lower house and share prices.
International Monetary Fund Managing Director Christine Lagarde said she was delivery some "tough love" to Britain.
Sterling fell towards its lowest in three weeks against the dollar, nursing losses for a second straight week.
Sterling fell to $1.4379 on Friday, with losses below $1.4375 set to take it to its lowest in three weeks.
Implied probability of an "In" vote remained steady on about 70 percent for the second week in a row, according to Betfair.
ICM poll taken May 6-8 put Out on 46 percent, In on 44 percent and 11 percent undecided.
QUOTES OF THE WEEK
"For 2,000 years, our affairs have been intertwined with the affairs of Europe. For good or ill, we have written Europe’s history just as Europe has helped to write ours...
"Isolationism has never served this country well. Whenever we turn our back on Europe, sooner or later we come to regret it. We have always had to go back in, and always at a much higher cost."
"Either we influence Europe, or it influences us. And if things go wrong in Europe, let’s not pretend we can be immune from the consequences."
"I think all this talk of World War Three and bubonic plague is totally demented frankly."
MARK CARNEY, GOVERNOR OF THE BANK OF ENGLAND:
"Now turning to the elephant in the room. The MPC judges that the most significant risks to its forecast concern the referendum."
"There is the possibility of negative spillover to global financial conditions because of uncertainty generated in this country."
"This issue is the number one issue that is raised with me and my colleagues every single time we meet a fellow central bank governor, foreign finance minister, head of a major corporation internationally, head of a bank, head of an asset manager, and I would say most domestic small and medium-sized enterprises that we meet."
PETER HARGREAVES, BILLIONAIRE STOCKBROKER BANKROLLING THE OUT CAMPAIGN:
"It would be the biggest stimulus to get our butts in gear that we have ever had," Peter Hargreaves told Reuters in an interview.
"It will be like Dunkirk again," he said, comparing it to the sealift when Britain was forced to evacuate its forces from Europe after France fell to the Nazis in World War Two, revered in British history as a moment the nation rallied to face mortal peril.
"We will get out there and we will be become incredibly successful because we will be insecure again. And insecurity is fantastic."