Staying longer in UK

Hello
My friend is coming to visit me end of January to stay for a week, she may stay for a bit longer upto 3 weeks maybe, depending on her circumstances back home in canada by end of January, at this moment she can only book a week.
If she did stay a longer after arriving, more than the week originally intended, would it cause an issue next time she came to visit me again in the U.K?
Thank you
Kevin

Should be okay.

vinny wrote:Should be okay.

But shouldn't that be seen in light of the duration for which the visitor VISA is granted and duration allowed by the Immigration Officer at the time of entry?

Yes. It's subject to the Immigration Officer's or Entry Clearance Officer's leave to enter endorsement. A Canadian does not normally require a visa to visit the UK. She may inform the Immigration Officer on arrival on her maximum intended duration of visit.

vinny wrote:Yes. It's subject to the Immigration Officer's or Entry Clearance Officer's leave to enter endorsement. A Canadian does not normally require a visa to visit the UK. She may inform the Immigration Officer on arrival on her maximum intended duration of visit.

Thanks. I completely missed the Canadian angle