Ambulance waits in Health Secretary Steve Barlcay's own constituency are among the worst in the country, figures have revealed.
Category one patients - the most severe - waited on an average of 14 minutes for an ambulance to arrive in Mr Barclay's parliamentary seat of North East Cambridgeshire.
The target NHS time for responding to calls involving life-threatening injuries, including cardiac arrest and serious allergic reactions is 7 minutes on average.
In an analysis of official data from the last year, the Liberal Democrats claimed Mr Barclay's local area has the ninth worst waiting time of any place in the country.
Liberal Democrat leader Ed Davey said: "These shocking figures show patients are facing dangerously long ambulance delays in the Health Secretary's own backyard.
“Ambulance delays can have devastating consequences for patients."
The party's analysis of NHS ambulance trusts' responses to freedom of information requests also exposes a stark rural and urban divide.
Patients in rural areas, the party said, are waiting 12 minutes on average for ambulances to arrive for Category one calls - 45% longer than urban areas.
The data comes after a shock poll found earlier this week that one in three 999 patients have made their own way to hospital amid record waits for ambulances.
The Liberal Democrats said the Tories have "allowed" the crisis in the NHS to spiral out of control after 13 years of governing the country.
Mr Davey added: "It is heartbreaking that people living in rural areas are being left waiting in distress and pain longer than if they lived in a city.
“Entire rural communities are increasingly being cut off from the basic health services they need, from getting an ambulance on time to seeing their local GP or dentist.
"It’s just another example of this Government taking rural areas for granted and allowing the NHS crisis to spiral out of control.
“We urgently need a rescue plan for health services in rural areas, starting by recruiting extra GPs and social care workers to take pressure off ambulance services and A&Es.”
A Department of Health and Social Care spokeswoman said: “We are working hard to improve waiting times which have substantially reduced from the peak of winter pressures in December 2022.
“Our Urgent and Emergency Care Recovery Plan will allow people to be seen quicker by scaling up community teams, expanding virtual wards, and getting 800 new ambulances on the road.
"This is on top of £750 million we have provided this winter to speed up hospital discharge and free up beds.”
An East of England Ambulance Service spokesperson said: “We have been working closely with our hospitals to reduce handover delays and get our ambulances back on the road as quickly as possible.
“Since the middle of January, there have been improvements in our response times for patients in both urban and rural areas, but we acknowledge there is much work to be done by us and our partners to improve these response times further.”
