A collapsible stroller comprising: a predominantly polymer handle frame ; a predominantly polymer front wheel frame ; a predominantly polymer rear wheel frame ; a hinge joint connecting the handle frame , the front wheel frame and the rear wheel frame for mutual angular displacement relative to each other about two spaced parallel metallic hinge axles; and a locking element at the hinge joint slidably moveable between an unlocked position in which the handle frame , front wheel frame and rear wheel frame are enabled to mutually rotate into a folded configuration, and a locked position in which the handle, front wheel and rear wheel frames are fixed to each other in an unfolded configuration; wherein the hinge joint essentially comprises a hinge housing of polymer material integrally formed with the polymer rear wheel frame , a spur-gear formation of polymer material integrally formed with the handle frame , the handle frame spur-gear formation configured for rotation about one of the hinge axles within the hinge joint , and a spur-gear formation of polymer material integrally formed with the polymer front wheel frame , the front wheel frame spur-gear formation configured for rotation about the other one of the hinge axles within the hinge joint and meshing with the handle frame spur-gear formation ; characterised in that the locking element is received and arranged to slide within a two-section groove extending transverse to the two hinge axles and defined partially within the handle frame spur-gear formation and partially within the front wheel frame spur-gear formation , the section of the groove in the front wheel frame aligning rectilinearly with the section of the groove in the handle frame when in the locked position; and wherein the hinge joint has at least two reinforced bearing surfaces adjacent the locking element when in the locked position, such that structural loads are transferrable between the reinforced bearing surfaces via the locking element. a predominantly polymer handle frame ; a predominantly polymer front wheel frame ; a predominantly polymer rear wheel frame ; a hinge joint connecting the handle frame , the front wheel frame and the rear wheel frame for mutual angular displacement relative to each other about two spaced parallel metallic hinge axles; and a locking element at the hinge joint slidably moveable between an unlocked position in which the handle frame , front wheel frame and rear wheel frame are enabled to mutually rotate into a folded configuration, and a locked position in which the handle, front wheel and rear wheel frames are fixed to each other in an unfolded configuration; wherein the hinge joint essentially comprises a hinge housing of polymer material integrally formed with the polymer rear wheel frame , a spur-gear formation of polymer material integrally formed with the handle frame , the handle frame spur-gear formation configured for rotation about one of the hinge axles within the hinge joint , and a spur-gear formation of polymer material integrally formed with the polymer front wheel frame , the front wheel frame spur-gear formation configured for rotation about the other one of the hinge axles within the hinge joint and meshing with the handle frame spur-gear formation ; characterised in that the locking element is received and arranged to slide within a two-section groove extending transverse to the two hinge axles and defined partially within the handle frame spur-gear formation and partially within the front wheel frame spur-gear formation , the section of the groove in the front wheel frame aligning rectilinearly with the section of the groove in the handle frame when in the locked position; and wherein the hinge joint has at least two reinforced bearing surfaces adjacent the locking element when in the locked position, such that structural loads are transferrable between the reinforced bearing surfaces via the locking element. <EOS>