RDRM36210 | Remittance Basis: Remittance Basis up to 6 April 2008: Occasions when there may not be a remittance: An overview of occasions when there may not be a remittance
From HM Revenue & Customs · Remittance Basis and Domicile Manual
In general, where the remittance basis applies it does not usually matter in what year the income arose, or the precise form of the remittance. However, prior to 6 April 2008 and the introduction of new rules defining what constitutes a remittance to the UK, there were some situations or anomalies in the rules dealing with Relevant Foreign Income (or Case IV/V income).