The Remain camp lost this one big time due to lack of leadership/unity in vision across party lines. The argument has been framed by Leavers as obstructionist politics in play (even Remainer’s voting for the motion bought into this false perception), rather than the accurate argument of ensuring a process of oversight/transparency based on what was/was NOT articulated in the referendum campaign. So in a sense we failed yet again to make our point crystal clear and by uniting under 1 clear message & vision. The lesson we should have learnt (and should now be learning) out of this is that however strong your political convictions unless you have the right leadership and strategy/campaign in place to take you there it is unlikely you will have any chance to effectively represent your vision successfully.
It is also fair to say that the way the referendum was conducted was flawed and is causing us grief because terms articulated by Leave camp were not properly documented and have not been clearly defined in ballot papers hence the confusion now about the terms. I personally suspect that if a legal challenge is invoked about the referendum process there could be potential it to be nullified or at least the government would not be allowed to proceed with triggering article 50 until such terms have been clarified/approved by the British people.
Finally, BREXIT referendum aside, it seems to me that Liberal/Progressive parties need to finally wake up/smell the coffee and learn to better strategise/collaborate and more importantly fightback aggressively if we are to reverse current trend signalling revival of ultra right protectionist/nationalist politics. We need to do a better job relating policies we stand for with actual liberal/progressive values we represent and suspect many electorates believe in-there just seems a disconnect between both hence the virtual La La Land we seem to be living in. We have a great/positive message & track record but do lousy when selecting the messenger and defining an effective strategy to follow. We need an aggressive turnaround because it is steep uphill curve we need to climb.