Plans to lift further lockdown measures on May 17 could be delayed if we see another surge in coronavirus cases, an expert has warned.

Boris Johnson’s roadmap out of lockdown has so far run on schedule, but the third stage of could be pushed back if there is a spike in infection rates as people enjoy more freedoms.

The Prime Minister warned at a Downing Street press conference this week that "there will be another wave of Covid" this year but said he expects the roadmap to remain on track.

He said: "I see nothing in the data now that makes me think we are going to have to deviate in any way from the roadmap cautious but irreversible that we have set out.

"But the majority of scientific opinion in this country is still firmly of the view that there will be another wave of Covid at some stage this year, and so we must – as far as possible – learn to live with this disease, as we live with other diseases."

But Professor Adam Finn, from the JCVI (Joint Committee on Vaccination and Immunisation), told BBC Breakfast: "The models that we've seen on JCVI clearly point to a summer surge in cases as the lockdown is relaxed, because there are still many people in the adult population who've not been immunised and who will therefore start to transmit the infection between each other.

"If people move too far forward with that too fast, we'll see things start to come up earlier.

"The sense that the problem is all over I'm afraid.. is a flawed one, we're still in a vulnerable situation, and there are still significant numbers of people who potentially could be harmed by this infection if this happens."

He added: "People want to have some kind of certainty and businesses want to know how to plan, but on the other hand I think it's always been presented as as a provisional timetable, based on what actually happens.

"I think if we do start to see significant rises in cases in some parts of the country, they may need to adjust back those dates in order to avoid the situation coming into effect.

"It's a bit hard to be definite about this because by definition it's uncertain."