My MGB is a rubber bumper to chrome bumper conversion so that means I’ve got two sets of front side lights – one pair in the combined indicator lights each side of the front grill and another pair of side lights in the headlights.
A couple of extra bright led bulbs from eBay, a relay and some wiring I converted the headlights into DRLs.
The DRLs only work with the ignition on – as soon as I switch the normal side and headlights on the DRL lights turn off.
There are many examples of DRL wiring circuits i found on the internet by searching “DRL WIRING CIRCUITS” – although it’s pretty straight forward.
Basically I took a feed from a spare fuse box terminal which was live when ignition on and a relay trigger from a connection in the sidelights wiring. You don’t have to worry about overloading an existing circuit as the power required for the DRLs is very low but I still put a 2 amp fuse in the feed to be safe.
The result is quite effective. I guess to do the same on an earlier car you would need a pair of rubber bumper headlights that have the integral side lights.
The diagram shows how to wire up the relay to the lights and power.
MGB tips mods and maintenance 