What do you change out of your jeans for?
If you’d been going to a nice restaurant for dinner after the Easter Service would that have made a difference to your outfit?
If you’d been invited to a family Easter Sunday dinner after the service by your MIL would you have worn something different?
I’m not part of the upper class set - my family roots are northern working class but we would always dress smartly for Sunday services (a bit more casual for weekday services but still not jeans) and always dress smartly to go to dinner at someone else’s house.