A radical design, the Leader was fully enclosed with an integral windscreen and was the first British motorcycle to have optional[2] flashing indicators.

[4] Designed by Val Page and Bernard Knight, The Ariel Leader featured a 250 cc two-stroke engine suspended from a monocoque 'backbone' fabricated from 20-gauge pressed steel panels.

As well as a full body, the standard Leader features included a headlight trimmer, an extendable lifting handle for easy centrestand use, and a permanent windscreen mounting.

[3] Factory listed options included: integral hard-luggage panniers, the first flashing indicators on a British motorcycle, a dash-mounted parking light, windscreen top-extension (adjustable on the move), a rear rack and a clock aperture built into a dashboard, which was closed by an Ariel badge when not fitted.

[8] In 1960, a prototype Arrow with a 349 cc twin-cylinder four-stroke engine was made to sell alongside the Ariel Leader.