Sri Lanka Aviation

As far as I am aware, dash 300s are not available at LGW. Please correct me if i am wrong.

You are right Banu, they only operate 772's out of LGW

Thanks, Is LGW convienient for north american passengers to take transit for CMB flight by BA?

Not really, a direct connection via LHR is still preferable.
LGW is poorly connected to North America via BA. However, there is a possibility that some budget airlines, such as JetBlue, WestJet, Norse, or Icelandair, could offer flights to LGW with good connections to BA on separate tickets. For the Sri Lankan expatriate community, this may still not be appealing due to visa requirements, baggage costs, and the inconvenience of transit, which involves going through immigration, collecting bags, and re-checking in.