Foreign Income - Holiday Pay in Arrears

Hi, I moved to the UK in 2019 on a secondment from my Australian employer. At the time of moving I had 8 weeks of annual leave accrued that would remain in Australia until I returned (although I was entitled at the time to have it paid out). This year I made the decision to make my stay in the UK permanent (I'm a dual national) and the company paid-out my accrued annual leave on the Australian payroll. As I'm a UK resident for tax purposes, my current understanding is that the payout will be reportable and taxable in the UK. However, I want to clarify whether the lump sum can actually be considered 'pay in arrears' as it was earned between 2017-2019 while I was tax resident in Australia and non-resident in the UK? PAYE70023 states 'Legally, an employee’s tax liability on a payment of arrears arises in the tax year that the employee was originally entitled to be paid the extra amounts, not in the year that payments are eventually made.' EIM02530 states 'Arrears of pay are earnings paid after the date when the employee should have received the salary or wages. For tax purposes, arrears of pay retain the character they would have had if they had been paid at the right time. Arrears are “earnings” within the meaning provided by section 62 ITEPA 2003. Also, HMRCs response to the question below advises that holiday pay is considered earnings. https://community.hmrc.gov.uk/customerforums/payepe/93d3eca1-1482-ed11-97b0-00155d9c7b3d#b81c57ae-cd86-ed11-81ad-6045bd0e73e7. Thanks

Hi scozzie,
EIM02530 advises that "arrears of pay may arise form an error on the employer's HR systems.
The employer or employee may discover that wages or salary paid in an earlier period were less than what should have been paid under the terms of the employment agreement.
The employer will usually calculate the arrears and pay them in a lump sum".
There is no error here, as you chose to not receive the annual leave at the time, you knew the earlier periods were less than what should have been paid.
 Arrears of pay would not apply in this case.
Thank you.