If you have a visa to Oman for a year or more, you can ask for your application to be processed in Oman which would actually have it sent to London, see
http://www.cic.gc.ca/english/information/offices/apply-where.asp#o or because you are Indian, you can opt to have it processed in India. The new rules are too new to have any history of timelines so it really can not be said at this point what the difference will be between getting processed in London vs. in India.