[en] In the 1983 CERN anti p p collider run, at √s = 546 GeV and with an integrated luminosity of 126 nb^-1, the UA2 collaboration observed 3 events containing a well identified electron produced in association with a large missing tranverse momentum and a hard jet or jets. These events were found difficult to be interpreted in terms of QCD W production. The absence of similar new events in the 1984 data sample, despite the increased energy (√s = 630 GeV) and the larger integrated luminosity (L = 310 nb^-1), makes the interpretation of the 1983 data in terms of standard QCD W + jet(s) production much more likely. In the total data sample, 128 events interpreted as W → eν decays with missing transverse momentum exceeding 25 GeV/c are observed in low background conditions. Of those, 31 events are associated with a jet of transverse energy exceeding 5 GeV. Including these events with hard jets, an average psub(perpendicular) sup(W) of 8.5 +- 0.8 GeV/c is measured. (author)