Surprised you haven't come across them before. I agree, it sounds like it is the Selectos burner.
The Selectos burners used to be fitted to several old boilers & the last variation of them was on the Myson (previously Thorn) Panda 50.
Getting rare now. Reliable British burners, if difficult to set up & some had fantastic British motors which go forever.
They also were on all the Thorn ODY boilers from the 1970s which were downdraft designs - boiler shell was L shaped & burner fitted high up with flame downwards. Unidare made in Irish Republic seem to have copied the design somehow.
I may have second hand spares for it & actually scrapped a lot. I have I think 2 "brand new" unused burners, might be of use to you & I have to very shortly remove a Myson 50 with a Selectos burner in lovely order.
Take a look on side of burner where you will find a metal plate with model number. Or take a photo or two of burner & perhaps electrodes & post it. There are different electrodes for certain models.