The requested information is not held in the administrative or finance systems of the Ministry of Justice (MoJ) or its predecessor bodies. To answer this question, the MoJ would need to collect the information manually and the costs of collection would exceed the disproportionate cost threshold. So far as I can recall I have used a taxi on three occasions since 1997 on official duties.
The Civil Service Management Code sets outs regulations and instructions to departments and agencies regarding the terms and conditions of service of civil servants and the delegations which have been made by the Minister for the civil service under the Civil Service (Management of Functions) Act 1992 together with the conditions attached to those delegations.
The Code can be accessed at the following website:
Paragraph 8.2 deals with travel and under this section departments and agencies must ensure that staff use the most efficient and economic means of travel in the circumstances, taking into account any management benefit or the needs of staff with disabilities.