So I contacted the West Yorkshire Archive with regards to the above and I have received this response from them today.
Does anybody have any bright ideas of how I can proceed. The information that I really need is the defendant's
"Thank you for your email received by us on Monday 22nd May 2017. Please accept my apologies for the length of time it has taken us to respond. I consulted the office Archivist about the best way for us to proceed with your enquiry as it contains some fairly complex legal issues. Here at Wakefield we do hold a number of court collections including the records of Pontefract Borough Court (collection reference P25) and the Upper Osgoldcross Petty Sessions Court (P19).
The Data Protection Act states the commission of an offence by a named individual is sensitive personal data. The introduction of the Data Protection Act in 1998 reinforced an already existing 100 year closure period on many records held in archive repositories. As such, any records less than 100 years old which contain sensitive personal data cannot be released to a third party by the West Yorkshire Archive Service.
Third parties are able to apply for access to information contained in sensitive records that are less than 100 years old, however they need to be able to prove the individual is deceased (as the Data Protection Act only applies to the living), or that they have the permission of the individual to whom the record relates to (the Data Subject). If you are interested in researching this particular case then it will be necessary for you to provide this evidence. This would relate to anyone listed in the case. So, if you are able to provide proof of the death of XXXXXXXXXX XXXX and XXXXXX XXXX then we would be able to release the information relating to them to you. We would however have to redact the defendant’s name in that instance.
Clearly in this case, the primary aim of your research is to identify the name of the defendant, so it is unlikely you will have proof of death or his permission to access the record. It is a confusing and frustrating situation in which we are unable to release information until we obtain proof of death or permission, but you may be unable to supply that information as you are not able to obtain it. You do seem to have a possible name to search for so if you were able to provide evidence of XXXX XXXXX XXX's death then we could undertake a search for that name on your behalf. I do hope this information will prove useful to you. I have attached our Data Subject Access Request form to this email which we would require you to complete and return to us if you did wish to access any information held in exempt records.
I do hope this information will prove useful to you but if you have any further questions then please do not hesitate to contact us again."
Any ideas, aside from waiting another 26 years?