Belfast sink with copper trap

[Outtheway]

Can anyone advise regarding the removal of the drain plug from the underside of the copper trap (situated under a belfast sink).
The sink has been in situ for almost 60yrs! & has been slightly dripping from the drain plug for some considerable time but unnoticed until recently (wet cupboard & kitchen floor).
Whilst it may end up with the whole pipework having to be replaced with plastic, i would like to see if the drain plug could be removed and if so whether a new washer would do the job as all the other pipework seems fine.
Has anyone removed this type of connection before?
What sort of washer would there be in the drain plug (if any)?
Any help/advice would be great, many thanks in anticipation!

[scotman]

Are you sure the trap pipework is copper?
What sort of material does the plug seem to be made of? Does it have flat edges that a spanner could grip? etc.

[AlBags]

Copper traps are still available. You will need a fibre washer to fix the old one.