A timeline of LS3/5A manufacture. Dates and numbers are approximate.
At the time of the re-design in 1987 Rogers continued to use 15 ohm labels on 11 ohm units. I estimate about 5,000 pairs with serial numbers between the early 31,000s and the early 36,000s are labelled like this and known by collectors as “Pseudos”.
Historically the BBC allowed 3 licences to be active at any time. The exception to this being Harbeth who, under Dudley Harwood, held a BBC licence from 1977 but did not start manufacture until 1988 under Alan Shaw.
Numbers are approximate number of pairs made not serial numbers