A QCD analysis using heavy vector boson data from the ATLAS detector at the LHC collected during the 2012 running period at a centre-of-mass energy of 8 TeV, where the boson was produced in association with at least one hadronic jet, is presented. Included in the analysis are ATLAS data on inclusive W and Z boson production at 7 TeV. The results are presented together with a new fit to the ATLAS inclusive W and Z data alone, performed with an updated parameterisation. The consequences for the strangeness content of the proton are discussed. Systematic correlations between the input ATLAS data sets are fully accounted. The resulting PDF set is called ATLASepWZWjets19.