As many readers will know, Anglican churches used to have a white light burning before the Blessed Sacrament ... as we do in the Church of the Holy Rood in Oxford, and as described in Betjeman's Lincolnshire Church and in his moving poem Felixstowe about the old nun, sole survivor of her Order,
... And all the world goes home to tea and toast.
I hurry past a cakeshop's tempting scones
Bound for the red brick twilight of St John's.
"Thou knowest my down sitting and mine uprising".
Here where the white light burns with steady glow,
Safe from the vain world's silly sympathising,
Safe in the Love that I was born to know,
Safe from the surging of the lonely sea,
My heart finds rest, my heart finds rest in Thee.
I remember hearing it once asserted that a white light before the Most Blessed Sacrament was what the Tridentine rules prescribed, and that red lights* were a Franco-Anglo-Irish RC corruption ... one example among so many of how we kept the rules so much better than they did (no, we weren't very nice people, were we?). Is there any truth in any of this?
*In heavily Gothic Victorian churches, we had (sometimes as many as) seven (vide Revelation cap 5 et alibi) red lights burning before the High Altar, but not as an indication of the Sacramental Presence which might have been on a side altar and which, wherever It was, had Its own white light. A red light would probably also burn before the image of the Sacred Heart, and a blue one before the Great Mother of God.