No.
But you may need to make them look nice and if they/it is installed in an escape route then....BS7671 521.11 comes into play.
521.11 Wiring systems in escape routes521.11.201 Wiring systems in escape routes shall be supported such that they will not be liable to premature collapse in the event of fire. The requirements of Regulation 422.2.1 shall also apply, irrespective of the classification of the conditions for evacuation in an emergency.
NOTE 1: Non-metallic cable trunking or other non-metallic means of support can fail when subject to either direct flame or hot products of combustion. This may lead to wiring systems hanging across access or egress routes such that they hinder evacuation and firefighting activities.
NOTE 2: This precludes the use of non-metallic cable clips, cable ties or cable trunking as the sole means of support. For example, where non-metallic cable trunking is used, a suitable fire-resistant means of support/retention must be provided to prevent cables falling out in the event of fire.