How do you mean?
The link that tonty posted explains the rules for all flights.
It has to be said that holiday flights out of LGW,are subject to less overbooking than the LHR flights, as 'no shows' are much rarer. I think the Vegas flight still fits into the holiday category, but it is the most popular of the LGW for conventions and there are a few business people that use it.
You can never say never, but I think the chances of being
forced off the plane are very, very small - there will always be those who volunteer - I have tried to volunteer on several flights, but never been successful.
Nick