It's the same here in the US. We often get called to people who, when asked "How long have you been having this pain?", say "Well, it started about a week ago". Oh good, so you decide to call for an ambulance now, at 10pm on a Saturday night. However, just recently someone told us that he's been having chest pain for about two or three days and it turns out, according to his 12 lead EKG, that he was having the "big one" today. So I guess it's not always a good indicator of how serious it is.