Morrison, R. v [2021] EWCA Crim 917, June 11, 2021, at paragraph 30:

Beyond the legislative requirements the relevant principles are now well established on the authorities. In summary, in assessing the appropriate period of disqualification, it is important to bear in mind, first, that the risk represented by the offender is reflected by the level of his culpability which attaches to his driving. There is a basic public protection purpose. Secondly, the main purpose of disqualification is forward looking and preventive, rather than backward looking. Disqualification is still an important element of the overall punishment for the offence and is intended to deter offenders and others. The court has a wide discretion in considering the appropriate length of disqualification. There is no formula by which a court can measure the right length. It is a judicial decision which should be tailored to the offender and the offence. It should not be so long that it disproportionately adversely affects the prospects of rehabilitation. In short, a balance has to be struck. The court should not disqualify for a period that is longer than necessary.