The following article from Encyclopaedia Britannica does not emphasize the fact, as the same encycopedia has when listing the "Sovereigns of Great Britain" that Sweyn or Svend was King of England from 1013-1014.
Sweyn I, byname SWEYN FORKBEARD, Danish SVEND TVESKAEG, Norwegian SVEIN TJUGESKJEGG, or TVISKJEGG (d. 3 Feb 1014, Gainsborough, Lincolnshire, England), king of Denmark (c 987-1014), a leading Viking warrior and the father of Canute I the Great, king of Denmark and England. Sweyn formed an imposing Danish North Sea empire, establishing control in Norway in 1000 and conquering England in 1013, shortly before his death.
The son of the Danish king Harald Bluetooth (Blatand), Sweyn rebelled in 987 against his father, who fled to Wendland (in Germany). Sweyn began feuding with Olaf I after the latter's accession to the Norwegian throne in 995, and he allied with the Swedish king Olaf Skotkonung and the the Norwegian Erik, the earl of Lade. The three allies defeated Olaf I in the Battle of Svolder about 1000, with Sweyn becoming virtual ruler of Norway, although nominally sharing sovereignty with his allies. Sweyn then turned again to England, leading apparently punitive expeditions in 1003 and 1004 in retaliation for the St Brice's Day massacre of Danes in England on 3 Nov 1002.
Sweyn did not again return to England until 1013, when he led a highly successful campaign and was accepted as king throughout the country, forcing Ethelred II into exile; but he died less than a year later. Although Norway returned (1014-16) to Norwegian rule under the leadership of Olaf II Haraldsson, Sweyn's Anglo-Danish empire continued under his son and grandson until 1042. [Encyclopaedia Britannica]
Note: The above text gives Sweyn's father as Harald "Bluetooth" (c 910 - 987), while the chart for the Ancestry of the British Royal House (United Kingdom) clearly shows Sweyn's father as Harald II King of Norway (living c 935 - c 970), son of Erik I Bloodaxe (d. 954). Clearly one or the other (probably the chart) is in error.