Child's bicycle - 20" wheels. 7-9 year old? (Heath Hayes WS12)

Child's Apollo road/mountain bike with 20" wheels. Been in the shed unused over winter, so just needs the tyres pumping up, a wipe over, and a bit of oil. Please note: the twist grip gear change does not work, but the bike pedals happily in one gear. Gear ratio can be changed manually at the sprocket.
Collection from Heath Hayes