These guns are in fact all made by FEG Budapest, the big Hungarian arms company. They were manufactured in their tens of thousands and exported to make hard cash for the communist state of that time. Relum was just the importer. Other companies imported to other countries (Grothaus in Holland for e.g.). The Jelly/Telly thing comes from a small metal name plate borne by some of them, which atcually says Telly, but is generally referred to as a Jelly (perhaps because of their debatable quality?). In fact they are good basic breakbarrels and there was also an underlever the famous, and perhaps less efficient Tornado. There was a whole range of different guns, from the 1960s until the very early 80s? All characterised by the use of double concentric springs and no spring guide. A piece of airgun history.
Relum no longer imports them, though one, the LG527 is apprently still made.