Dear [name of employee]
In my letter of [date] I set out the terms and conditions relating to an offer of alternative employment as [job title]. Within this letter I explained that you were entitled to a trial period of four weeks in this job. This trial period [ended/ends] on [date].
[Unfortunately, I have to inform you that we do not consider that you have met the standards required during this trial period. Specifically, [set out any specific issues here]. Therefore, from [date] your employment in this role will terminate owing to redundancy from the date you were made redundant from your previous role as [job title] on [insert date]. You will receive your redundancy payment of £[statutory plus any contractual/ex gratia], together with your contractual notice pay [which will be paid in lieu] OR [you will be placed on garden leave for the duration of the notice period*].
I am sorry that this situation has arisen. [If any suitable alternative employment does occur in the next [number] weeks during your notice period, I will contact you to discuss this].
Yours sincerely
(* Check the contract to ensure you have a contractual right to place the employee on garden leave.)