Thanks!
This seems to work and not make a mess of everything else
set security nat source rule-set SNAT_use_interface rule snat_exclude_ipsec match source-address <Local-Public-IP-external-int>/32
set security nat source rule-set SNAT_use_interface rule snat_exclude_ipsec match destination-address <remote-GW-public-IP>/32
set security nat source rule-set SNAT_use_interface rule snat_exclude_ipsec match application junos-ike
set security nat source rule-set SNAT_use_interface rule snat_exclude_ipsec then source-nat off
//Robert