Before revision:  Those estimates are larger than the ONS's respective counts of 531, 3432, and 6139 COVID-19-associated deaths  , implying that the ONS's counts underestimate rather than overestimate the true death toll.
After revision:  The ONS's respective counts of 531, 3432, and 6139 COVID-19-associated deaths , implying that the ONS's counts underestimate rather than overestimate the true death toll.