Ariel Owners Motorcycle Club

I have helped a friend to rebuild his 1934 250cc which we have just got running for the first time. The engine is the pre enclosed rocker box type with the chrome plated side plates supporting the rocker gear. The top end sounded a bit noisy and it got me thinking about how are the rockers and rocker shafts lubricated. There was nothing on the bike as purchased. The rocker shafts are drilled , which would suggest that they should be fed with oil but seems to be nowhere to take an oil feed from to supply them.
There are two small pipes that appear to supply the valve guides that join together with a connection that points toward the right hand side support plate but have no apparent way to connect to a feed pipe.
Can anyone help with this conundrum?

If you feed oil to the rockers, where would it drain to? The drilled shafts should be fed grease to lube the rockers. There should be a grease nipple in the end of each.