I ran simple query below and it gave me results:

select Id, name, userrole.name  from user

The child relationship name is called 'Users' on the User object so I was initially the query below but it kept erroring out:

select Id, name, users__r.name  from user

I thought every call to a parent must have '__r' appended but not in this case plus it doesn't even use the relationship name i.e. users. Can someone explain why the first query worked and the second one didn't...Many thanks...