Prince William and Kate Middleton are not the only ones fretting about the weather and worrying over the organisation of their big day. London will be holding 500 of the expected 4,000 street parties to celebrate the royal wedding across England and Wales.
In the capital, Wandsworth is top of the league table, with 49 of its streets expected to close so that residents can celebrate. Close behind is Croydon, with 48 applications for road closures and then Richmond, with 44 streets planning a party. Islington council has waived fees for arranging street closures while the Government is urging all local authorities to cut red tape involved in closure applications.
Even David Cameron is said to be considering holding a party in Downing Street (he has applied to Westminster city council for a licence - though technically, the Prime Minister's road is always closed).
In Tower Hamlets, Mayor Lutfur Rahman has got round the problem of what you do if you live in a tower block by announcing a picnic in Mile End Park.
And London Mayor Boris Johnson, with actress Barbara Windsor as his "street party champion", is urging boroughs to go all-out to use the occasion to rebuild a sense of community. The number of people living alone in the capital has doubled since the Seventies, he says, and will triple by 2020. "Sixty per cent of Londoners do not feel a sense of community in their local area," warns the Mayor.
Sarah Boud, a theatre administrator, is holding a royal wedding party in Wanstead, east London. The Redbridge council fee for closing her road of Edwardian terraces, which started at £1,600, has been slashed to nil, with a little pressure from her local Labour MP John Cryer. There will be barbecues in front gardens, a cake-making competition and a bouncy castle for the children (which parents are paying for).
Mother-of-two Tanya Gass of Beckenham, a lawyer married to a banker, is paying £112 insurance for the street party she is helping to organise for about 100 people living in 60 houses. The idea started at a local book club - "but it has been a steep learning curve", she says. The local primary school is lending tables and people will bring chairs, and food to share. Everyone will wear a badge with their house number, and the organising committee will wear "keep calm and party on" T-shirts.
Meet the neighbours
Most councils now have street party guidance on their websites, or you can consult the excellent Streets Alive (streetparty.org.uk) founded in 2001 to foster street parties nationwide. Says director Chris Gittins: "It's not so much about being friends as being friendly and looking out for one another."
Typically, people meet about eight new neighbours, he adds. He suggests "street meets" as an alternative to a full-blown party. "Use the pavement, a garage forecourt, a driveway, or a front or back garden, for a tea party, BBQ or small street picnic. It may be more basic with fewer people - but it's easier and very worth it."
Gittins even believes street parties enhance property values: "People want to live in a friendly street."
The Royal Parks welcome "informal picnics" but different parks have a different "maximum group" size, from 20 in Bushy Park to 40 for Regent's Park, Richmond Park and Hyde Park. Check out the regulations on royalparks.gov.uk.
So what's the secret of party success?
PR director Karoline Newman has organised 10 of them in her central London public square, involving the local residents' associations.
"Needs are quite basic," she says. "Everybody should have a drink. Food can simply be crisps, quiche, sausage rolls, bread, cheese and grapes - but decide in advance who is bringing what. We ask everyone to register at a central table, contribute towards costs and receive a name badge."
Plan ahead for emergencies. Then there's the weather of course - have contingency plans and ways to communicate them, says Newman. She has the church hall on standby, and encourages gazebos to create "a little tented village."