Reading the messages here one would be inclined to think that thousands of major roads are going to be closed to traffic and bring London to a standstill, cause big congestion problems.
Who would want to close a whole width of the road or the whole length? You would select a quiet road.
The general consensus is that very many people more or less the whole residents in the road presumed thousands in some places, but there are many who would not partake, as they are anti social. I do not think that there will be large parties.

Organisers can only be held responsible if known. In my experience other than telling your close neighbours that you are having a Street Party just to get their feelings and whether they would if held participate, it is then up to the persons to just come out of their houses and bring something for the needs of the party.
This is a spontaneous occurrence, any organised party would cost you a lot of money.

The thing that should be remembered is that the Country has been invited to have street party’s.
Would the authorities be able to Police all of those or just the rowdy ones.
Any case taken to court for non notification of holding a street party, would not be looked on as acceptable as it was an invitation to partake in the Royal Occasion for rejoicing.

It would be unthinkable for me to tell the public that I will not be in my home on this day, or any of the other people that had their names included on the list of intended people attending a street Party.
In these uncertain days it is not advisable to give your whereabouts at a specific time.
Read the news the next day. White Van Hire had its most successful day every van was out on hire.
Boot sales are well stocked this weekend buy back your valuables.

Yes I have been on real Street Party's.
There is always a person who thinks that they are in some way an authority to instruct you on what you should do, be your own person do what you want.