How to search for whether I have used any passwords starting with letter A and ending with letter B

How about exporting your data to a CSV file and then sorting the password field in Excel or Numbers?
You can quickly search for the pattern you are looking for.

http://https://support.1password.com/export/

Thank you for your answer! However, I'd rather not export all my passwords into plain text as that kind of defeats the object of storing them securely in the first place.
Should I take it from your answer that there's not a way to do this in 1Password?
And if so is there a way I can suggest this as a future enhancement? I think it would be useful for many people since this seems to be a standard alert that Experian produces.

Thank you again for taking the time to reply :-)

Hello @LilacCow! 👋

I'm sorry to hear that some of your personal details may have been compromised. Did your monitoring service tell you the email address associated with the password that was leaked? If they did then you can search for that email address to try to narrow down the list of items to look through:

Search in the 1Password app to find what you need

There's isn't a way to search for a password pattern by just entering the first and last character of a password. I've let our Product team know that you'd like to see this feature in the future.

I also recommend that you use Watchtower to see if it can flag any of your logins as having been compromised: Use Watchtower to find passwords you need to change

-Dave

ref: PB-33979611