A hospital trust failed to meet government A&E waiting time targets - and is one of the worst in the country for delays.
The North West London Hospital Trust is among the five worst out of the 145 trusts surveyed in research by House of Commons Library.
The trust’s accident and emergency departments, which includes Northwick Park Hospital, saw 87 per cent of patients within four hours for the 2013/2014 year.
All hospital trusts in England have been set a target of seeing 95 per cent of patients within four hours in accident and emergency departments.
MP for Harrow West Gareth Thomas has raised concerns over waiting times and funding at Northwick Park.
He said: “This shows there are real pressures on the NHS in Harrow and Northwick Park.
“We know Harrow is not getting its fair share of funding due to issues with the new funding formula and there is also the impact of costs of the reorganisation of the NHS.
“The closure of the A&E department at Ealing and the downgrading of Central Middlesex will also have an impact on Northwick Park Hospital.
“The investment being spent on the hospital’s new A&E department is of course welcomed, but whether it will be able to deal with the increased strain remains to be seen.”
Director of operations at North West London Hospital Trust Tina Benson said: “We don’t believe that any patients should wait more than four hours within our emergency department and we are working hard to improve this.
“There has been a big increase in the numbers of patients arriving at Northwick Park Hospital by ambulance and we are working with all our local health and social care providers to develop alternative ways of treating patients to reduce the need for them to have hospital treatment.
“Our new £21 million emergency department will open later this year. It will be closer to other emergency services, such as acute assessment and intensive treatment units, operating theatres and wards, which will make the service more efficient for patients.”