I, unfortunately, have nothing to do with this 'An Indian Summer' ... I am just quite kicked having found my blog's namesake! [courtesy my sister in London, who by the way, is supposed to be preparing for her final thesis submission and not surfing the net for festivals to attend! ;-)]
You can find more details on the festival yahan, yahan aur yahan. (Translated from Hindi: here, here and here)
So Londoners and people visiting London - do drop into Regent Street's 'An Indian Summer' on Sept 2nd, and let us know of your experience by dropping in a comment on this post!