The coupling device (9) comprises a first connector part (10) and a second connector part (11), the connector parts (11, 10) comprising connecting portions (16a, 16b, 13, 14) for engagement with corresponding connecting portions (16a, 16b, 13, 14) of the other connector part (11, 10). A disengagement means (12) is provided for assisting in disengaging the engagement between the connecting portions (13, 14, 16a, 16b).
