As I said, the condition says gate entrance must be stopped up as per approved plans. The plans say block entrance with matching stone. Hence the condition is that a wall at the gate entrance must exist and must be like the existing wall at that time. The removes the PD rights for that section of wall as under PD you could change the wall look, dry stone to fence for example, or open plan even.
Plans typically contain a lot of information but not all of that is turned into planning conditions. Planning condition guidance says that conditions should only be imposed where they are necessary for the plans to be passed. There is no reasonable justification for this condition. The given reason is highway safety but for that it should just say vehicular access via entrance is forbidden, it does not need to impose a wall in perpetuity. Also, the previous plans (still in force at the time of this application) granted an access at this point so there can be no safety issue.
Hence all one can say is the condition was inserted by mistake, it has no justification and it is invalid. There is no explanation for the need of the condition in the planning file, it just appears in the officer's report having been on the earlier plans too. I suspect but cannot prove that the condition was a requirement from the parish council which falsely claimed to own the highway land at this point. If so it had no right to be a planning condition either. Best case is planning and highways were negligent. Worse case, they conspired with the parish council to prevent the lawful use of the highway. If they did then they didn't write it down so far as I have been able to find. I can prove the parish council claimed to own the land and that this was false and that the land is highway and that planning advised then to forbid access across "their" land in order to frustrate planning permission. All of that is written down in the planning files.