s 55 Meaning of “qualifying trigger”
(1) This section applies for the purposes of section 54. (2) A loss of self-control had a qualifying trigger if subsection (3), (4) or (5) applies. (3) This subsection applies if D's loss of self-control was attributable to D's fear of serious violence from V against D or another identified person. (4) This subsection applies if D's loss of self-control was attributable to a thing or things done or said (or both) which— (a) constituted circumstances of an extremely grave character, and (b) caused D to have a justifiable sense of being seriously wronged. (5) This subsection applies if D's loss of self-control was attributable to a combination of the matters mentioned in subsections (3) and (4). (6) In determining whether a loss of self-control had a qualifying trigger— (a) D's fear of serious violence is to be disregarded to the extent that it was caused by a thing which D incited to be done or said for the purpose of providing an excuse to use violence; (b) a sense of being seriously wronged by a thing done or said is not justifiable if D incited the thing to be done or said for the purpose of providing an excuse to use violence; (c) the fact that a thing done or said constituted sexual infidelity is to be disregarded. (7) In this section references to “D” and “V” are to be construed in accordance with section 54.