  Resistivity under pressure and magnetization measurements on
Ba$_{1-x}$Sr$_x$VS$_3$ single crystals with 0 $\leq x \leq$ 0.18 and no sulphur
deficiency show an abrupt onset of ferromagnetic (FM) order at a critical value
$x$=0.07, concomitant to a change of the magnetic properties at the
metal-insulator transition (MIT) and to a collapse of the unit cell at ambient
temperature. A reduction of the MIT temperature to 50 K upon $x$ that scales as
the V-S distance is also observed. This gives evidence of a chemical pressure
induced quantum phase transition that stabilizes the incipient FM order of
BaVS$_3$. The $0.07<x$ results suggest a coexistence of FM and metallic phases
at larger $x$.
