Hi Janine
No you dont need his permission .... when a child is born before 2003 to unwed family the father has no parental rights.
this means in order for him to gain these rights and stop you he would have to take you to court any apply for them, obviously giving valid reasons why after 7 years he needs/wants them
You need to sign the forms including all parties who have parental rights aka you and leave the other side blank
I went through this in October last year and immigration said at 1st that i needed a court order confirming sole custody. I challenged this !! It was then referred to Canberra head office and i was told , and i quote "Oh your right, how funny, no one in the office knew that"
Lovely !!
So no you dont need his permission to take them, i would imagine they will ask but you could put a covering letter stating that only you have parental rights to your children and under english law are allowed to remove them from the country.
The reason they like to make it easy for them selves is as part of the hauge convention if they let you in and he HAS got parental rights they would be classed as harbouring a fugitive who kidnapped their children.
My visa was stopped unless i was prepared to go to court but after a few legal googling and a few sleepless nights i was proved right.
Hope this helps