Upminster and Willesden were some of the areas worst hit by recent postal delays, a study has found.

Royal Mail faced problems all over the country over the festive period due to short staffing, illness during the pandemic and "resourcing issues".

Now a Citizens Advice study has found Upminster, Chelmsford and Willesden were among the worst affected areas, with many residents experiencing weeks of “severe disruption” to deliveries.

The figures are based on an online survey of 4,165 UK adults carried by Yonder Data Solutions, which asked participants of their experience of letter delays between mid-December 2021 and mid-January 2022.

Findings suggested 2.5 million people around the UK missed important documents, health appointments, or were unable to pay a fine or bills, sometimes resulting in further penalties.

A Royal Mail spokesperson confirmed the impact of Omicron had a “particular impact during Christmas and January, with approximately 15,000 staff members off work due to sickness and self-isolation at one stage”.

However, on March 4, the postal service said it has had no reports of service issues and additional staff have been drafted in to ensure post is delivered on time.

Hornchurch and Upminster MP Julia Lopez said: “This incredibly helpful report by Citizens Advice confirms our frustrations and concerns around Christmas deliveries in our constituency.”

The study notes that disruption peaked in mid-January, with 77 areas across the UK affected, but the “situation has finally appeared to improve”.

Royal Mail’s spokesperson added: “The number of offices we have reported as being most impacted by service issues has reduced from 77 to none, as of Friday, March 4.”

Apologising for the delays, the spokesperson said Royal Mail is “working hard to equalise performance and improve service in impacted areas, including spending over £340 million on overtime, additional temporary staff and sick pay, as well as targeted support”.

Ms Lopez said she has worked with Royal Mail to ensure contingency plans are being put in place so RM14 is not “as impacted should a similar situation arise”.

She hopes this will prevent residents going through “similar challenges again, particularly when some of the post includes critical medical appointment letters”.

The Royal Mail spokesperson added: “Our postmen and women are continuing to work incredibly hard, as they have done throughout the pandemic, and we are thankful for all of their efforts and determination.”

This comes after this newspaper revealed a woman received little post for weeks in Upminster.