Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
Name the written by for john trefor

### Inputs:
table_name: table, columns: ['Series No.', 'Episode No.', 'Title', 'Directed by', 'Written by', 'UK Ratings (BBC2 Rank)', 'Original air date']

### Response:
SELECT Written by FROM table WHERE Directed by = John Trefor