Cambridge Grammar of English Hardback with cd-rom a comprehensive Guide

Negative subjunctive

435e

The subjunctive mood is rare in English, but it occasionally occurs following 

verbs such as insist, recommend, suggest, expressions of necessity such as it is

important/essential that

, and conditional subordinators such as if, lest, on

condition that

, unless. The negative is formed with not plus the base form 

of the verb:

He had tried to call her during the week, but she had 

insisted that he not call

her at home and there was no other number he could try.

Her father had had a slight stroke and the doctors 

recommended that he not

travel.

[TV presenter introducing a woman who has agreed to a secret interview]

She agreed to be filmed 

on condition that we not show her face.