Passport and visa question

Hi,

My other half is here on a dependent visa and has just sent off their passport to our home country for renewal.

I would like to know whether they need to get a new visa in the new passport or whether they can carry their resident card and old passport when they travel.

If the new passport needs a new visa, how do we go about this, please? I've looked online but can't find clear, up to date information.

Thank you in advance.

by SteveSteveSteve-O