Dame Janet Smith: "Colossal" workload

Shipman is at Frankland Prison, County Durham, serving 15 life sentences for killing 15 women.

When the inquiry began in June last year the team agreed to investigate the deaths of 466 of Shipman's former patients.

The interim report had been expected at the beginning of the year.

"The work entailed in the individual decisions has been far greater than was envisaged at the outset," said Dame Janet.

"In the end, we will have examined more than 800 deaths and the report will contain about 500 individual decisions.

"Each of these cases has been individually investigated by the team and each of those 500 cases will have a decision which has been written by me personally.

"I hope that will give you an impression of the amount of work that has been done and is still being done. It is colossal."

Second stage

Dame Janet said she would personally be "deeply disappointed" if the report was delayed further.

She revealed that one of the problems the inquiry had encountered was "the discovery of further evidence at a late stage".

Only last week, she said, the team found documents meaning that some cases will have to be reopened and new material considered to see whether the decision the inquiry team had made was valid.

The inquiry will now hold one more hearing before the second phase begins in May.

The second stage will look into the initial investigation by Greater Manchester Police into Shipman's practices, in March 1998, that failed to bring the GP to justice.