Tamper evident closure to prevent refilling

A closure (10) is provided and comprises a base (15) attachable to a container. The closure comprises an engagement insert (250) receivable in the base and including screw thread formations (255) for engaging corresponding formations on a container neck. The base and insert comprising a co-operating uni-directional rotation arrangement (171, 265) which prevents rotation in a direction of screwing onto a container neck but allows relative rotation in a direction of unscrewing, whereby to prevent unscrewing of the closure. Inner skirt (170, fig 9) and outer skirt (165, fig 9) may be provided and a top deck (160, fig 12), including an annular notch (165, fig 12) of material thinning may be provided, if an attempt is made to remove the closure defamation/and or breakage of the top deck occurs.