NHS Surcharge paid after premium service payment

Hi,
I paid and booked appointment for premium service on 1st July but I did not pay my NHS surcharge on that day because I sent my passport to my embassy for change of name and NHS surcharge payment site requires my passport number...
I later paid my NHS surcharge on 22nd July... When I received my new passport
My premium service appointment is on the 10th of August

I want to know whether it is a must to pay NHS surcharge before paying for premium service?

don't think so. IHS number is needed by UKBA, and should be written on application front page. As long as you do that, you should be ok i believe.

Thanks..
I called UKBA and they said the same..thanks