18a, M?a??, London police arresting a Knight on purpose.
19d, ???????, Group of three making small journey.
23a, A?????t, Give job to petty officer splitting a beer.
24d,?????, Ride bike round bend finally, ring bell.
26a, 4words, 6.2.3.4. M????? O? The Mood, Here you'll find White Stripes music that's rather bland.
27, R?????, Tell the churchman losing head.