The character's name is Jirik (George) in Czech. Probably it was translated as Martin in Wales.

Try this: http://www.bontonland.cz/film/pohadka/Zlatovlaska-110077.html?lang=3 They have an option to display the site in English (Click on the Union flag on the top left of the screen).

Try this link: http://us.imdb.com/board/10070894/

Thank you to Barry and Petra, youve come up with exactly what I was looking for. Ive tried to see if Zlatovlaska is available to buy, and there is a video available in Czech only (on a Czech website) but I dont understand enough Czech to be able to order it. Is Zlatovlaska popular in the Czech Republic I wonder?
I have another query now, maybe this will be harder to answer. I remember another serial in the 70s, at least it was shown as a serial in Wales, but Ive never found reference to it anywhere. It was called in English 'Desert Adventure' and I dont think it was Czech. Ive always thought it was from Poland, but Im really not sure. I can remember kids breaking up for school holidays, I believe travelling by train.then somehow the action turns to a desert country (somewhere in Africa I presume). There are scorpions, kidnappings, hostage-taking.that kind of thing, I remember it being very good.but does anyone else remember? and what country was it from? what was it called in the original language?
Again I'd appreciate any help.

the name is Zlatovlska (1973)dir.Vlasta Janekov
i hope you can find it! good luck!

There is a made for TV film from
Czech TV called Zlatovlaska (see IMDB)
which might be what you are looking for.
This name meens "golden-haired" or "Goldilocks"
but my Czech-English dictionary says that it is
from a fairy tale and the cast list means a King
as one of the characters although there is no
trace of a "Martin".
Can seem to find any reference to it on any
Czech pages for cassettes, but you could do
a search using this title and VHS.
Best regards
Barry Appleby