From: Chris Heaton-Harris Minister of State (Department for Transport).
The Government is committed to ensuring deaf people can fully participate in society. We understand that mandatory use of face coverings will be difficult to adhere to for some. That is why there are exemptions to the rules for some disabled people and those with certain health conditions on public transport.
You also do not need to wear a face-covering if you are speaking with someone who relies on lip-reading and facial expressions to communicate. We are working closely with transport operators to make sure that their staff and passengers are aware that not everyone is required to wear a face covering. Our Safer Transport guidance includes a clear reminder to transport operators of the need to provide staff with disability equality and awareness training.
In addition to this, the guidance also specifically provides warnings that conventional coverings can prevent many disabled people from accessing oral information and instructions. Our guidance for operators and more information on face coverings can be found HERE.
NOTE: It is advice, there is no legal backing to it, and this is a suggestion for public transport ONLY, NOT the NHS.