LONDON (Reuters), – Boris Johnson, British Prime Minster, apologized for not disclosing a conversation with a Conservative Party donor at the head of an inquiry into how his flat was funded. The letters were published on Thursday.

Johnson’s Redecoration at Downing Street has been under scrutiny for both its cost and the source of funds. The scandal is one of many that plagued Johnson at the close of the last year.

Lulu Lytle, a well-known London interior designer, has yet to be seen the redecoration. However media reports have described it as including expensive wallpaper and bizarre furniture.

Johnson was initially informed by media reports that Johnson had paid out tens of thousand of pounds in invoices. Johnson eventually repaid him the donation.

Johnson was cleared of violating the rules. However, critics have used the incident to challenge Johnson’s ethics. This is in addition to other instances that have placed Johnson’s judgement under scrutiny. Johnson has been accused by opposition politicians of leading a corrupt government which gives favors to its cronies. He refutes this accusation.

Johnson addressed a letter to Christopher Geidt (the independent advisor on ministers’ interests), stating that he was unable to recall the exchange, and that “security concerns” had prevented him access to an old device.

In a letter dated Thursday, Dec. 21, he stated that he was sorry for the Office of the Independent Adviser being placed in this situation and could only offer an humble and sincere apologies he gave during our discussion earlier this day.

In a separate investigation, the electoral watchdog discovered that the so-called “missing trade” was also being investigated. Johnson’s Conservative Party was penalized by the watchdog because it incorrectly reported donations that were used to finance flat refurbishment.

Geidt stated in a December 17 letter that he hadn’t changed his original conclusion published in May. This cleared Johnson from any conflict of interest, but criticized him for failing to scrutinize the funding.

Geidt made more general criticisms in his Thursday letters, pointing out those processes which meant that he didn’t see the messages. Geidt said withholding any information was not wise.

Johnson received a separate response dated Dec. 23, in which he stated that the episode “shaken my confidence because potential and actual failures of process occurred at more than one portion of the apparatus for government”.