Advice on indicator warning light problem

Purple cloud

Hi all

Newbie here. Just picked up our privately bought secondhand caravan and need some advice already!!

Is it a legal requirement to have an audible or visual signal in the car to tell if your indicators are working on the caravan?

We've just had a new tow-bar fitted on our Honda CRV and we have neither, much to the amazement of the very helpful seller of the van.