But the 42-year-old former Leeds director of rugby has excelled during his short time in charge and has now been given a full-time contract until January 2016.
Despite his relative lack of international experience, Lancaster held off stiff competition from ex Springbok supremo Nick Mallett at the final interview stage, with John Kirwan being overlooked earlier on in the process and Jake White ruling himself out due to his commitments with the Brumbies.
"We have been through a rigorous and global selection process and are confident that Stuart is the right person to lead England Rugby forward into the 2015 Rugby World Cup," said new Rugby Football Union chief executive Ian Ritchie.
"He has shown throughout the 6 Nations and subsequently in both interview and other conversations I have had with him that he has the skills and vision needed to be England head coach.
"I am sure everyone in England will join me in congratulating Stuart on his appointment. He can be assured of my support and that of everyone in the Union."
Lancaster will now look to build on recent wins over Scotland, Italy, France and Ireland as his focus turns to the summer tour of South Africa and the 2015 World Cup.
England head to the home of the 2009 Lions conquerors for a three-Test series in June but much has already been made of the need to succeed when the country hosts the game's premier tournament in three year's time.
"I am immensely honoured and proud to accept this role. From the hundreds of messages I received during the 6 Nations I know what supporting England means to millions of people and I am privileged to be involved," said Lancaster.
"I want to thank Ian and the selection panel for giving me the chance to explain my vision for England Rugby and, with their backing, I feel very positive about the future.
"The players, coaches and the management were superb during the 6 Nations and it's down to them that we made such positive steps from when we first met up in Leeds. The challenge now is to take this squad and the players we will see emerge forward to 2015. It is one that I can't wait to get stuck into.
"We have a massive task ahead of us in South Africa this summer and we have 37 games before that first World Cup match on home soil, so every second counts in developing players who can win that tournament - which has to be the ultimate aim."
Assistant coach Graham Rowntree also looks certain to stay with England under Lancaster but the RFU face a tough task in requesting that Saracens release fellow assistant Andy Farrell from his contract in order to join England on a full-time contract.