Blair Alston netted a last-minute winner as Falkirk strengthened their prospects of finishing as Scottish Championship runners-up by beating St Mirren 3-2 at home.Alston converted his 11th goal of the season - and third in four games - with a back-post finish as the Bairns claimed a first victory in three attempts.Lee Miller had headed Falkirk into a ninth-minute lead after Jack Baird directed Myles Hippolyte's cross into his path, with the latter having a goal ruled out for offside just after the half-hour mark.St Mirren levelled 11 minutes into the second half when Stevie Mallan curled a free-kick into the bottom corner from the edge of the box after Tom Taiwo was booked for handball - his 12th goal of the season.Substitute Bob McHugh nodded Falkirk back in front with 20 minutes remaining following a goalmouth scramble before Mallan's second, from a cut-back, made it 2-2 after 82 minutes before Alston struck.