@artkavanagh i did not - but just been reading up on it .. including

Larry Hagman, who portrayed "J.R. Ewing" in the television series Dallas two decades later, was brought aboard for the last two episodes to help fill in for Young, who had been the lead in most of the episodes.

.. no further explanation as to why he needed help.

And just one series - and you can tell it is American - THIRTY episodes - that's 5 to 6 SERIES of a UK show!