In most cases, a Deed Poll is not required when a woman simply wants to change her name to her maiden name upon being widowed. Usually, the marriage certificate and husband’s death certificate certify the name change and act as a valid evidence.
However, there might be a requirement of Deed Poll where the death certificate of the husband and marriage certificate are not accepted as evidence (e.g. financial institutions). In such a case, a widow's Deed Poll is guaranteed to be accepted by all organisations as documentary evidence of a name change.
A Deed Poll is definitely required if a widow wishes to change her surname to anything other than her maiden name. Please visit the UK Deed Poll Office's general information page for name change eligibility details, application information, and related FAQs.