So when judges retire and wish to embellish their pensions, they rejoin their old chambers and hang out their shingles that say "arbitrator and/or mediator". They are no longer advocates, they are quasi-judges instead. It is probably slightly preferable to becoming the English equivalent of Judge Judy.
It seems that the bar itself is no longer so enamoured of its judicial brethren returning to skim their work: "One magic circle set member said judges in arbitrations has now become "an overheated market"."
Frankly, this is all very childish. In the US judges can retire and join law firms as lawyers. They even appear in court, often with the honourific title, "Judge." Some become attorney general or head a government agency. Over here we think that it is unseemly for judges to abandon their olympian ideals in favour of partisan advocacy.
It is also a restrictive practice without justification. If a judge wants to become an advocate again, then the market will adjudicate on his or her fitness to practise. The clerk will soon announce that a change of direction into another line of work is to be preferred if the work isn't there.
Perhaps as judging is becoming more specialized--needing tickets to be a family judge or commercial judge and so on--we should reconsider the basic qualifications for a judge. Is being an advocate truly the most appropriate credential? Why not make judging a career choice out of law school as in Germany, for example. However, let's leave the last word to that searing critic of human malaise, E L Wisty, as he lamented:
Yes, I could have been a judge but I never had the Latin, never had the Latin for the judgin', I never had it, so I'd had it, as far as bein' a judge was concerned. I just never had sufficient of it to get through the rigourous judging exams. They're noted for their rigour. People come out staggering and saying "My God, what a rigourous exam!" - and so I became a miner instead. A coal miner. I managed to get through the mining exams--they're not rigourous, they only ask one question, they say, "Who are you", and I got 75 per cent on that. I'd rather have been a judge than a miner. Being a miner, as soon as you are too old and tired and sick and stupid to do the job properly, you have to go. Well, the very opposite applies with judges.