An employee has been employed for 5 years, but has never had a contract written up although an oral contract agreement was made. This was when it was just the Managing Director and the CTO. Now the company has grown and all new employees have contracts, this employee also requires one. In addition, the title of the employee will be changing (salary will stay the same) from Director of Operations to Production Manager. This is just a title change to reflect his duties better, again due to the fact the company has grown.

What elements are needed to ensure he doesn't have a case for constructive dismissal? What else should we be aware of in regards to writing up this contract? Should it be dated with the original employment date (I assume so or he wouldn't have the same employment rights as a long term employee)? Should it also have the date the contract is agreed and signed?

Thank you in advance for your help.