In theory, no witnesses are required, but in practice it’s advisable to have one, or ideally two, who can vouch for your presence and signing of it in case of any later disputes, and some organisations are reasonably less-likely to accept unwitnessed or under-witnessed deeds poll as a result.

You can go ahead with an unwitnessed deed poll if you like, but expect to have a harder battle getting it recognised by authorities.

As with any signature, it’s highly-advisable not to use an erasable medium, like pencil.