When does the cam belt on a Vauxhall Corsa need changing?

I'm buying a second hand Vauxhall Corsa for my son - it's a 1.2 litre on an 02-plate. When should the cam belt be changed?
The 1.0 and 1.2 are chain cam engines. The 1.4 is belt.
Answered by Honest John on

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