Dave Lewis, the new chief executive of Tesco, has said that he wants to take the troubled retailer back to its core values, but said that he would not be making any “knee-jerk” reactions.

Speaking in a video posted on the retailer’s YouTube channel, Lewis said his first week in charge had been “quite a rollercoaster” but would not shy away from the “difficult calls” that need to be made.

Lewis, who made no mention of Giraffe or Harris + Hoole, said: “I do think it’s pretty clear we have to get back to the core of our business in price, availability, and service. What it is that customers need from us so that they reward us with their loyalty.

“Will there be changes? Let’s be honest, there has to be. We don’t want the trends affecting our business to carry on. If I need to, I will change things. I will make those calls.

“I am not naïve to the position of the brand and the reputation. But I only see that as an opportunity. The great thing about brands is it is easy to talk but actually you change reputation by doing.

“I am going to spend some time listening, spend some time learning and observing from colleagues as to what it is they think we could be doing.

“The great thing about brands is it’s very easy to talk but you change reputation by doing. We have 320,000 staff in the UK and we touch so many people, if we can change how it is they experience us then the opportunity to turnaround that reputation is massive. We need to change our behaviour if we want to change our reputation.”

Lewis says that while he has lots of “ideas, thoughts and questions” about the steps needed to rebuild the brand, he will not be jumping to a simple solution and will instead take the time to listen and learn from staff about where Tesco should focus its efforts.