Please see Diagram 513.1A at Schedule 2, Part 3, Item 4 of the Traffic Signs Regulations 2016, for the current version of this sign.
UK Traffic Signs Manual - Chapter 4 Warning Signs. (2013)

Figure 23-1; Fira Sans substituted for proprietary font used for text in the original
Source file supplied as EPS to uploader from Department for Transport; 

https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/226765/traffic-signs-manual-chapter-04.pdf
Department for Transport (United Kingdom)
Department for Regional Development (Northern Ireland)
Scottish Executive
Welsh Assembly Government