The facts are there, do a quick google.The information about closer union was presented to the British people in Parliament by the PMs of the day.
I have just done a quick google and I found this in the BBC archive from 2001;
Secrets of 1970 revealed
"Documents disclosed under the 30-Year Rule reveal that the most controversial European issue of today-monetary union-was already being discussed at the highest levels of government in 1970 as the UK sought entry to the club."
"British documents seen by the public for the first time have revealed how in 1970 the government" ... "dithered over what to tell the public over Europe."
"papers reveal that the government's thinking appeared to be to downplay sovereignty issues out of fear of losing public support."
"While the media concentrated on what would happen to the prices of daily goods in the new Common Market, papers reveal that officials and the Prime Minister himself were already considering whether or not their membership of the new club would lead to European monetary union."
news.bbc.co.uk/1/hi/uk/1095248.stm
UK Confidential Monday, 1 January, 2001
UK downplayed sovereignty in Euro talks
"At the negotiating table, they could hardly be avoided as Brussels had already devised what became known as the Werner Plan, a proposal for monetary union."
"According to the senior British officials who saw it, the plan "could imply the ultimate creation of a European federal state with a single currency."
"It will arouse strong feelings about sovereignty and provoke vigorous discussions."
news.bbc.co.uk/1/hi/in_depth/uk/2000/uk_confidential/1094207.stm