What is correct formalwear for a solemn evening Church service?

[ZugIslandProdigy]

Many of our Roman Catholic friends here in London have just concluded a lengthy, formal evening Church service - the Solemn Pontifical Vigil Mass of Easter, which ran from 20:30 to 23:00 at Westminster Cathedral. Traditionally, full morning dress was the correct clothing for Easter Mass in London, so a staunch sartorial traditionalist will accept that for the Solemn Pontifical Vigil Mass, some kind of formal clothing is in order. But we also know both white and black tie outfits are inappropriate for wearing in Church, due to their louche associations: these are clothes for drinking, dancing, gambling and seduction, and not worship.

This leaves us with a question: what is the appropriate formal clothing for the most solemn of Church services in the evening? Is it simply white tie - meaning I am wrong about white tie being party clothing? Alternatively, is there no extant formal dress code for this situation? What if I wore a black cutaway coat (or frock coat) with matching black trousers and waistcoat for Church services after 18:00? What if I wore a black lounge jacket with striped trousers and an odd vest for Church in the morning, and wore the same jacket with matching black trousers and waistcoat for Church in the evening? I feel I may have discovered a consistent use case for the black lounge suit suit.

This is a question of more than theoretical interest to me, since I am Russian Orthodox: we very frequently worship in the evening, and so once I hit the lottery, I will bespeak one of the above options...

 

[ZugIslandProdigy]

One more option I did not mention would be to wear regular morning clothing even to evening Church services. I could conceive of making this exception specifically for Easter, because the Easter service often ends as the sun rises, and because the events commemorated on Easter occurred in the early morning, but it seems quite incorrect for any other day.