Perhaps the Council is not so "pooey" after all!
With firm resolve, I have pursued the street party issue further. I contacted Streets Alive, and cried on their shoulder via email. And in their reply they encouraged me to dig a bit deeper.
With good result:
a.) It turns out that the information I found on the Council website regarding street party policy is most probably out of date. Councils across the country have made the decision to waive the street closure charges for parties and gatherings in honour of the Royal Wedding;
b.) private events taking place in quiet residential roads or cul de sacs are exempt from the lengthy paperwork larger gatherings require.
I seem to be learning a valuable lesson. Life in Britain is like being sculptor, working in marble or stone. You must chip away at it, slowly, but steadily.
Tap, tap, tap...