Hmmm being a bit of a muppet on this one!
Having manually gone through all of the various database upgrades it appears that update_db_to_1_8_6.sql and update_db.sql are identical so thats sorted. However the documentation clearly states that any updates need to be done but that update_db.sql does the required updates from the last release so I workd on the assumption that this made changes from 1.8.6 to 1.8.8.
Hey Ho.
Take care
David D.
The Historical Reenactment Web Site
http://www.histrenact.co.uk