Charles de Gaulle was right already in 1967:

"Compared with the motives that led the Six to organize their unit, we understand for what reasons,
why Britain-who is not continental, who remains,
because of the Commonwealth and because she is an island, committed far beyond the seas,
who is tied to the United States by all kinds of special agreements-did not merge into a Community
with set dimensions and strict rules.
While this Community was taking shape,
Britain therefore first refused to participate in It and even took toward it a hostile attitude as if she saw in
It an economic and political threat.
Then she tried to negotiate in order to join the Community,
but in such conditions that the latter would have been suffocated by this membership.
The attempt having failed, the British Government then asserted that it no longer wanted
to enter the Community and set about strengthening its ties with the Commonwealth and with
other European countries grouped around it in a free-trade area.
Yet, apparently now adopting a new state of mind,
Britain declares she is ready to subscribe to the Rome Treaty,
even though she is asking exceptional and prolonged delays and, as regards her,
that basic changes be made in the Treaty's implementation.
At the same time, she acknowledges that in order to arrive there,
it will be necessary to surmount obstacles that the great perceptiveness and profound experience
of her Prime Minister have qualified as formidable."

Out 2016.