Sorry for beiong a bit tardy in responding clancybob. There is only a requirement to report where damage/injury has been caused and where it was not possible to exchange details at the time. Road Traffic Act 1988, Section 170 (confirmed by Highway code, para. 260):
(1) [In the event of an accident]� owing to the presence of a motor vehicle on a road, an accident occurs by which�
a) personal injury is caused to a person other than the driver of that motor vehicle, or
(b) damage is caused�
(i) to a vehicle other than that motor vehicle or a trailer drawn by that motor vehicle, or
(ii) to an animal other than an animal in or on that motor vehicle or a trailer drawn by that motor vehicle, or
(iii) to any other property constructed on, fixed to, growing in or otherwise forming part of the land on which the road in question is situated or land adjacent to such land.
(2) The driver of the motor vehicle must stop and, if required to do so by any person having reasonable grounds for so requiring, give his name and address and also the name and address of the owner and the identification marks of the vehicle.
If for any reason the driver of the motor vehicle does not give his name and address under subsection (2) above, he must report the accident.
(a) to a constable, or
(b) to some person who, having reasonable grounds for so doing, has required him to produce it,
To comply with a duty under this section to report an accident �the driver
(a) must do so at a police station or to a constable, and
(b) must do so as soon as is reasonably practicable and, in any case, within twenty-four hours of the occurrence of the accident.
So it seems the issue is whether EmmaKaryn considered any damage was caused. If she believes not it will be for the prosecution to prove that there was.