Great find !
The Master 610K was the early version of what later became the popular Beomaster 900K.
It's not really a Beomaster since this radio still followed B&O's previous
model name convention but of course the use of the Beomaster model name in the Ebay title
may attract more buyers.
It does not have the little green stereo lamp at the front and
the shortwave button does not have the usual "K" for "Kort" (short)
but instead "F" for "Fisker" (Fisher) since they were the heavier users
of the short-wave band.
Looks nice.
BTW: This photo is believed to be of a prototype, it does not have the dial memory
bar with the little sliding pointers:
Martin