Note, Office for National Statistics (ONS) figures differ from Public Health England (PHE) data, which only count COVID-19 deaths of people who have had a positive test result confirmed by a Public Health or NHS laboratory.
PHE data does not include deaths of people who had COVID-19 but had not been tested, people who were tested positive only via a non-NHS or Public Health laboratory, or people who had been tested negative and subsequently caught the virus and died. In short, PHE set a high bar for reporting COVID-19 related deaths.
When it comes to ONS data, I am interested in looking at all registered deaths — irrespective of the cause of death listed on the death certificate. ONS data on COVID-19 deaths relies on the clinical judgement of the doctor issuing the death certificate. However, by looking at all registered deaths in any given week, we can nevertheless monitor mortality rates as they compare to average trends.