Honest answer first: nothing in the Dulux range lands bang on Edward Bulmer Sang de Boeuf. The two nearest are Dulux Sicilian Summer 1 (LRV 11, ΔE 4.4 from the original) and Dulux Terracotta Army (LRV 12.4, ΔE 4.5). Both are close enough to read as the same family on the wall, but at ΔE 4.4 to 4.5 a sharp eye will spot the difference side by side — that's well above the ΔE under 2.5 we'd call a proper match.
Why the gap? Sang de Boeuf — "ox blood" — is a deep, slightly browned oxide red, and Edward Bulmer mixes from natural earth pigments, which gives it a depth and a soft, dusty quality that mass-market formulations struggle to replicate exactly. Sicilian Summer 1 is the warmer, slightly more orange of the two Dulux options; Terracotta Army leans marginally more earthy, which is why I'd nudge most people towards it as the truer feel.
The "but they look the same on the chart" trap: deep reds shift more than almost any other colour depending on light and sheen. In a north-facing room both Dulux options will flatten and cool; in warm evening light they'll glow. The original Bulmer holds its character better across that range because of those earth pigments, so if the breathable, low-VOC, heritage feel is what drew you to Sang de Boeuf in the first place, the Dulux match gets you the colour but not the soul of it.
Practical advice: buy tester pots of both Dulux options, paint a big A2 board (two coats, proper sheen), and prop it against the wall morning and night before deciding. If budget is driving the swap, Terracotta Army is my pick. If you genuinely love Sang de Boeuf for what it is, pay for the real thing on a feature wall and save the Dulux for the larger areas — nobody will clock the difference once it's all up.