Skip first flight and get on at layover stop?

Question

So, I am going to be flying from Paris to the US in September, and I will have a layover in London at Heathrow. I am hoping to actually be in London ahead of time, and just skip my first flight, and simply take the flight from Heathrow to the US straight, skipping my first flight from Paris to London. Is this possible? Do the airlines realize what you're doing and like cancel your ticket or anything? I am doing this because it's cheaper than switching my flights and simply flying from London to the US. It's British Airways, if that makes a difference.

Answer 1

You can't do that, the airline will cancel any remaining flights if you miss the first or any leg of your flight. This is true of all airlines.

Answer 2

If you do this without informing the airline, your entire ticket will be cancelled. The fares are made specific from city to city, so if you break it apart you are changing around your fare structure. Whaty I am saying is that your ticket may have been alot more expensive if you had originally bought the ticket with a London departure point.

Sometimes if you call the airline they will make exceptions. But you probably have to come up with a really good excuse to have them let you do it. In general, they wont.