If you are looking for your ASA Membership Number whilst completing your Application Form, you can normally find it using the Swim England webiste for Individual Best Times (also useful place to look for swimmer gala PBs, Past performance and tracking progress)
If you go to the following web page, enter the Family Name and “Go Looking” (You may get an “I am not a Robot” box to tick, scroll down the list of names and you will see the Club they are associated with as ORCA (Royton) – (some may list as Oldham Aquatics SC if they were ATS members before joining ORCA) – amd their ASA membership Number is on the left.
Whilst you are there – If you then click on the membership number you will see where their Individual Gala results are listed – Any of the items shown are in Blue they are clickable and you can dig into Split Times on >50M races, Past results and all sorts of data from past galas. (of course that is when you have done some galas !)
You can also go looking at everyone elses !