The chairman of Royal Mail has apologised for gaps in its service over Christmas, as parcel carriers faced their busiest ever winter.

The company said is retaining around 10,000 of the 33,000 temporary workers who helped it out over the festive period.

At its peak, the business carried 11.7 million parcels in one day – almost a third more than during the peak of the first national lockdown last spring.

That was part of the 496 million parcels delivered over the last three months of 2020 – an all-time high for the business.

“Given these record volumes, we recognise that at times our service during the period was not always as we would have wished,” said chairman Keith Williams.

“But, thanks to the efforts of our team, the retention of around 10,000 of the 33,000 flexible workers from the Christmas peak, and the introduction of new processes, we have been making encouraging progress.

“We are resolutely focused on delivering a comprehensive service despite the challenging circumstances.”

Royal Mail now expects to make an operating profit “well in excess” of £500 million in the financial year ending in March.

Revenue in the first nine months of the financial year hit £9.3 million, a rise of nearly 14%.

The number of parcels it delivered rose by 31% to £1.3 billion, while letter numbers dropped 14% to 5.6 billion.

The company said the third quarter had been driven by Christmas and Black Friday, and that tighter Covid-19 restrictions in November and December had made people shop online more.

So far in January, the company’s parcel wing is still performing well, seeing growth of 37% as nationwide Covid-19 restrictions were introduced at the start of January. Many people are also returning unwanted Christmas presents through the post.

Julie Palmer, partner at Begbies Traynor, said: “Royal Mail remains one of the largest couriers in the UK and has shown its willing to innovate and reshape itself to meet the new demands of its customers.

“The introduction of parcel hubs will add greater efficiency and help to offset the drop in letter volumes, while potential new contracts from the growth in e-commerce could help to keep the business on track.”