I would recommend two things;
1) If there was an accident in the UK, the HSE would get involved, they would be the people who would make the investigation. You can contact them for advise, they do have people who specialize in the warehousing sector.
2) I'm guessing as a trainer, you must keep your certification up to date every three years or so by using an external company to train the trainer. I would recommend calling them for advise.
If I were you, I would point out, you do not make the rules, you only follow the safe working practices of the training provided to you by the company you work for and if they feel you are unfair, they should consult an external RTITB representative for a second opinion.