"31st October is the official deadline for applications, both to your LEA and here. However this falls in half term so you should ensure your SIF is received by us before Thursday 25th October 2012 (the school is closed for an Occasional Day on Friday 26th October)."
From the Useful Information for Admissions PDF which can be found here:http://www.watfordboys.org/index.php?option=com_content&view=article&id=5&Itemid=10
The SIF for the other schools in the SW Herts Consortium must be submitted by tomorrow as far as I know.
Don't forget to complete your CAF by 31st October too.