Would having tenants ,no legal agreement ,invalidate Buildings Insurance ?

[gingeroots]

A friend let her flat to a couple ( friends of tenant in flat below ) with nothing in writing ,just a verbal agreement .
This was for a few weeks ( 4 or 5 ) after the orginal tenant moved out and while flat was put up for sale .
Unfortunately the couple have caused a pretty serious fire ( candles ) which has burnt out a room in the flat and caused damage to flat below .
Does anyone know whether the insurance is likely to be invalidated because no formal tenancy agreement ?

What kind of insurance did she have - personal or landlords? Was there accidental damage cover?

Umm - my friend owns the flat and there is buildings insurance that covers all 3 flats .
It's a house divided into 3 flats and the arrangement is that the 3 owners are members of a company that own the freehold of the building .
Think that's correct - it's an alternative way of sharing the freehold .

Unless she had landlords insurance then it's likely the insurance company will decline the claim on the basis that the property was being let out.

I think she must have had landlords insurance ,she's never lived in the flat herself and it's been let for several years to a tenant who has now moved out and flat on market for sale .
The owner of top floor flat manages the freehold company thing and is incredibly organised so don't think any chance no landlords insurance .

We have a holiday flat that is in a similar property. We have to provide a statement to the insurance company providing the buildings insurance each stating about our letting and how often the property is visited. We then have separate holiday property contents insurance.

Thanks Lizcat .