Markham Peking House
Just tried to find out more info. They haven't closed, they've just renamed themselves. Royaljelly was right, they're now called King of Kings and can be reached at the same phone number/location: 905-479-0818.
Going tonight to try their peking duck, so I'll post my thoughts afterwards! I'm a die hard Chung King fan, and I've been going there for the past 10 years so hopefully they stand up to their peking standards!