Whilst employees have certain rights to privacy, it is not unlawful to use CCTV in the workplace. However where the use of CCTV has any adverse effect on employees this must be justified by the benefit to the employer eg: there are thefts taking place in the plant area which they are unable to prevent by other means.
You've mentioned that consent has been given to have cameras in the warehouse - so it sounds as though some sort of consultation process has been carried out with employees or their unions about this. Is this correct? Has the employer carried out a similar process in relation to installing cameras in the plant as well?
The employer should provide you with reasons for now wanting to install cameras in the plant - particularly as guidance given under the Data Protection Act suggests that you should be aware of the extent and reasons for any CCTV monitoring that is carried out.
Employers should also:
1. Ensure workers are aware that they are being monitored and why - a suggestion is that they put a notice up on a noticeboard in the area where monitoring is taking place;
2. If the employer is using monitoring to enforce rules and standards of work, employees should clearly understand what these rules and standards are;
3. Any information obtained through monitoring should only be used for the purpose the CCTV cameras were installed in the first place - unless of course the information obtained from monitoring discloses an activity that no reasonable employer could be expected to ignore eg: breach of health and safety which puts employees at risk or potential criminal offence.
4. Keep the information obtained securely and ensure that it is kept no longer than necessary and it is deleted when it is no longer needed eg once it has been used in taking disciplinary action against an employee.
I hope you've found this answer useful.
Best of luck