Do I need an isofix base with an primo viaggio ES carseat

[JenJen84]

as title please, do I NEED one? Or can I use it with the seatbelt running across the front and then behind?

I can't seem to get a conclusive answer.

No you don't need an isofix or a sure fix base, we used ours with just the seatbelt.

However, do go and check as it doesn't fit in all cars. It doesn't fit in a ford focus for example without the extra height boost the sure or isofix base provides.

Thanks very much :)