The Indian High Commission in London has now outsourced their visa application process to the firm which already handles visas for several other countries (including, for example, Russia). You must go via that company (VFS Global) as India House no longer deals with visas:
http://www.vfsglobal.com/India/UK/
Hopefully though, they might be rather more efficient than India House used to be!
The current fee is £102.00 plus VFS's £7.44 service charge, totally £109.44.