The dates of birth and death don't make sense

St Kenelm, Clifton-upon-Teme, Worcestershire
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Saint Kenelm (or Cynehelm) was an Anglo-Saxon saint, venerated throughout medieval England, and mentioned in the Canterbury Tales. The church was notable for the large numbers of slate memorials in the floor.

 The dates of birth and death don't make sense. William appears to have died nine months before he was born.
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