But until this week, no-one knew what they meant. Sievey died in 2010, leaving no clues about the secret messages dotted around the borders of his record sleeves, footballprogrammes and fan newsletters.
Manchester-born Sievey was a cult star throughout the 80s and 90s, and his story was told in Michael Fassbender’s 2014 Frank. Several well-known stars passed through his Oh Blimey Big Band – DJ Mark Radcliffe and documentary maker Jon Ronsson were both members and the band’s driver was Virgin Radio DJ Chris Evans.
But Sievey let none of them in on the secret of the code – which he made trickier by mixing with nonsense symbols drawn by his children.
Steve Sullivan, who made a documentary film about Sievey and his bizarre round-headed creation, spent a lot of time trying to crack the code.
He took the rows of symbols to several codebreakers an puzzle experts, but none of them could help.
“It was entirely plausible that there wasn’t a code there and that he was just winding people up.”
He told BBC News: “My own attempts to crack it proved absolutely futile. I spent a while just looking at them going, ‘What could he be saying, what could this mean?’
“But it was impossible to crack them, and it was entirely plausible that there wasn’t a code there and that he was just winding people up.”
Eventually he asked if the government’s monitoring and cyber security experts at GCHQ would be willing to help.
Even they were baffled until Steve mentioned that Sievey’s son Stirling told him his dad would get the kids to fill an outer row with random symbols, while Sievey would insert his actual code into the inner row.
“It meant the outer row triangles is a complete red herring,” Steve said. “Not only did he put a mystery out there, he made it deliberately impossible to crack.
“By letting his kids add nonsense into the message, it deliberately obscures the chances of anybody – even top mathematicians – being able to crack it.”
“So I reported back to GCHQ that the outer ring is a red herring and then had an email one day saying, ‘Right, we’ve cracked it during a light-hearted training exercise.'”
But Frank had the last laugh: “I’m embarrassed to say, on the very next day Chris’s very own code grid was found in the back of his address book. It was almost like Chris Sievey was going, ‘There you go, now we’ve all had our fun, there’s the explanation.’”
Once deciphered, the coded messages turned out to be little soundbites about Sievey’s career as Frank. One, for example, read “Why does my nose hurt after concerts?”, a reference to the huge paper maché head Sievey wore to disguise himself as Frank and the swimmer’s nose clip he wore on his nose underneath it to help him perform Frank’s strange squeaky voice.
Steve says: ”It was just an exercise in wilful absurdity…
“But then all of his work was an exercise in wilful obscurity and absurdity. I think he loved the idea that he was putting communication out but people didn’t even know he was communicating.”