Like the factory

fence the lead hand will not keep an aggressor at bay for
ever -just long enough for you to initiate verbal dissuasion,
escape or a pre-emptive attack - but it will place you in
charge, even though your aggressor may not know it. Placed
correctly the lead hand will not only maintain a safe gap, but
it will also disable the attacker's armoury (right and lefthand
techniques! head butt etc). Although the aggressor may not
realise this on a conscious level, he will instinctively
understand that, until that fence has been removed or bypassed,
his techniques have no clear way through.
The lead hand should be held in a non-aggressive way and
should not touch the aggressor unless he makes a forward
movement and tries to bridge the gap between you and he.
The lead hand acts as an antenna to your aggressor's
intentions. If he moves forward, he will touch the fence and
set your alarm bells ringing. This forward movement should
be checked so as to maintain the safe range by using the
palm of the lead hand on the aggressor's chest. Don't hold
the touch, as this may be seen by your assailant as a
controlling movement. Whilst of course it is a controlling
action, it's better, at this stage that the aggressor does not
feel that you are in control, this creates a power play and
may force him to knock your hand away or grab your wrist
and possibly cause him to attack you pre-naturely.