Easter

What to do if you play something in the wrong key? I did this once before with a communion hymn after the anthem and started again but on Sunday I played the start of the last verse of Thine be the glory in E flat from the Rawsthorne book having been in D and realised during the first line so reverted to D. It must have sounded very wrong! But I put it down to tiredness and loss of concentration having been up at 4.30 a.m. and playing for 2 long services. Imogen remarked on the finale and I said too loud - I thought she meant the Howells but maybe not!