s 690 Power of limited company to purchase own shares
(1) A limited company having a share capital may purchase its own shares (including any redeemable shares), subject to— (a) the following provisions of this Chapter, and (b) any restriction or prohibition in the company's articles. (2) A limited company may not purchase its own shares if as a result of the purchase there would no longer be any issued shares of the company other than redeemable shares or shares held as treasury shares.