This is not a difficult one. The date can be narrowed down to c1895. Standard guage stock (so after 1892); the clothes (no ghastly big Edwardian female hats, but one male in the background is wearing a silk topper -not, I would say, a common sight at Redruth station today!). The fashions pre-date the Edwardian era, so it's got to be mid- to late 1890s. Signal post probably post -1894, when box opened.
All the best -I enjoyed the coverage of LR open day.
Roy Many thanks Roy.