In the early 1980s, the BBC Computer Literacy Project was in full swing. The BBC Micro was a staple in schools, but as the decade progressed, the landscape changed. The introduction of the "Owl" computers (the BBC Master series) and the rise of business travel created a demand for a computer you could take on the road.
There have been various branded novelty or "surprise" portable radios produced under license, though none officially carry the "Thea" moniker in major collections like the British Library Sound Archive Modern Digital "Surprises": You may be referring to the BBC Sounds thea bbc surprise portable
You cannot catch a surprise if you don't know where to look. Since you are actively searching for "thea bbc surprise portable," you likely want specific episodes. Here is how to forecast a surprise drop: In the early 1980s, the BBC Computer Literacy
Technical possibilities