Anytime my friend.
It never gets too hot or too cold here.
You will ALWAYS find tourists in London (so don't imagine you can some when there are none).
It's most beautiful (like all of Europe) in late spring or early summer (April to June) but London suits the rain and the weather so come in November and bring a coat : )
The travel time between London to India (Bangalore) is 9hr and 30 mins and travel time between India (Bangalore) to London is 10hrs and 30 mins.
The Eurostar travel time from London to Paris is approximately 2 hours and 15 minutes.
Delhi time is ahead of London.
It takes about 11 hours to travel by plane from London to Seoul, Soth Korea.
train
9 hours
An unusual time such as winter
Train from Paddington
The average Eurostar travel time between London and Paris is around 2 hours and 15 minutes.
approximately 9 hours
2o hours
Two days.