Lillelien was a popular and engaged commentator. It was not unusual for people to turn off the sound on the TV and listen to him on the radio instead. Lillelien quoted by a colleague: "We shouldn't necessarily make a boring radio programme even if it is a boring football match. We should make a sports show that excites people". As a person he was often introvert and quiet, the opposite of his on-air persona.
In 1948, he went to Northwestern University to study journalism. After going back to Norway for his military service, he got a job in the newspaper Fremtiden. But it didn't take long before he was working for the Norwegian broadcasting network.
In 1963 a long working relationship with Håkon Brusveen started in the cross country races at Holmenkollen. The olympic champion from the 1960 Olympics would be standing somewhere by the ski track and give his view on the competitors' performance as they passed. This collaboration would last for the rest of Lillelien's working days. Brusveen went on working for NRK after Lillelien's death.
“Your boys took a hell of a beating” 
Most famously, he commentated on Norway's 2-1 victory against England in a World Cup qualifier in Oslo on 9 September 1981. At the end of the match, alternating between English and Norwegian, he proclaimed (in Norwegian) "We are best in the world! We have beaten England! England, birthplace of giants", before taunting a roll call of famous English people, usually quoted in an edited, English-only form as follows:
- "Lord Nelson, Lord Beaverbrook, Sir Winston Churchill, Sir Anthony Eden, Clement Attlee, Henry Cooper, Lady Diana, vi har slått dem alle sammen, vi har slått dem alle sammen [we have beaten them all, we have beaten them all]. Maggie Thatcher, can you hear me? Maggie Thatcher [...] your boys took a hell of a beating! Your boys took a hell of a beating!"
Full Norwegian/English version 
The full Norwegian/English version reads as follows:
- "Vi er best i verden! Vi er best i verden! Vi har slått England 2-1 i fotball!! Det er aldeles utrolig! Vi har slått England! England, kjempers fødeland. Lord Nelson, Lord Beaverbrook, Sir Winston Churchill, Sir Anthony Eden, Clement Attlee, Henry Cooper, Lady Diana--vi har slått dem alle sammen. Vi har slått dem alle sammen.
- "Maggie Thatcher can you hear me? Maggie Thatcher, jeg har et budskap til deg midt under valgkampen. Jeg har et budskap til deg: Vi har slått England ut av Verdensmesterskapet i fotball. Maggie Thatcher, som de sier på ditt språk i boksebarene rundt Madison Square Garden i New York: Your boys took a hell of a beating! Your boys took a hell of a beating!"
Translated version 
The full version, completely translated to English:
- "We are the best in the world! We are the best in the world! We have beaten England 2-1 in football!! It is completely unbelievable! We have beaten England! England, birthplace of giants. Lord Nelson, Lord Beaverbrook, Sir Winston Churchill, Sir Anthony Eden, Clement Attlee, Henry Cooper, Lady Diana--we have beaten them all. We have beaten them all.
- "Maggie Thatcher can you hear me? Maggie Thatcher, I have a message for you in the middle of the election campaign. I have a message for you: We have knocked England out of the football World Cup. Maggie Thatcher, as they say in your language in the boxing bars around Madison Square Garden in New York: Your boys took a hell of a beating! Your boys took a hell of a beating!"
Although the commentary was for Norwegian radio, it soon made its way to an English audience, and became quite famous in England. The election campaign was the Norwegian parliamentary election of 1981, which was held on 13 and 14 September of that year.
Parodies and homages 
In 2002 Lillelien's words were designated the greatest piece of sports commentary ever by The Observer's Sport Monthly magazine. Such is its place in British sporting culture that parodies of the commentary have been written to celebrate domestic sporting victories, such as the following when the England cricket team beat Australia to regain the Ashes in September 2005:
- "Kylie Minogue! Steve Irwin! Holly Valance! Crocodile Dundee! Natalie Imbruglia! Ian Thorpe! Mrs. Mangel! Can you hear me? Your boys took one hell of a beating!"
- "Dame Kiri te Kanawa, Peter Jackson, Neil Finn, Sir Edmund Hillary, Jonah Lomu - we have beaten them all! Helen Clark, can you hear me? Your boys took one hell of a beating!"
- "King Olaf, Roald Amundsen, Liv Ullmann, Edvard Munch, Vidkun Quisling, Thor Heyerdahl, Henrik Ibsen, Edvard Grieg, Monty Python's Norwegian Blue, Morten Harket, and Anni-Frid from ABBA. You boys took a helluva beating!"
The Deputy Editor of the Daily Record at the time, Murray Foote, since issued an apology for the inclusion of Vidkun Quisling in the quotation:
- "While I naturally assumed Quisling was not one of Norway's favourite sons, I was truly unaware of the deep loathing his name engenders amongst your countrymen.
- Had I been aware of this, I would not have used his name and I apologise unreservedly for the offence it caused."
In advance of the Scotland v Norway game at Hampden on 10 October 2008, a parody was created by Tennent Caledonian Breweries (sponsor of the Scottish National Team) for radio and subsequently animated and posted on YouTube.
Following Manchester University winning University Challenge against the University of Cambridge Pembroke College in March 2012, a commentator for the Manchester student newspaper observed "We have beaten Pembroke College, Cambridge! Cambridge, birthplace of giants. Rab Butler, Clive James, Ted Hughes, William Pitt the Younger, Eric Idle, Peter Cook, Bill Oddie! Bill Oddie, can you hear me? Your boys took a hell of a beating!"
- Saken er klar! (1985)
- VM-boka. Mexico, Maradona og andre høydepunkter. (1986, with Tor Røste Fossen.)
- Aftenposten 22 June -85
- Aftenposten 16 March 1985
- in fact England went on to qualify for the finals, while Norway were eliminated, eventually finishing bottom of the qualification group.
- Original recording on NRK website
- Observer - The 10 greatest bits of commentary ever
- Tribute (in Norwegian) on NRK website
- Newspaper commentary on the Daily Record article and the inclusion of Quisling (in Norwegian)
- Article describing official apology from Daily Record (in Norwegian, with full apology in English)