A packer for anchoring and sealing to a tubular in a well, the packer including a packer element, an anchoring arrangement, a setting mechanism and a release mechanism. The release mechanism holds a thin-walled section of tubing in the packer in tension using a biasing mechanism. On severing the tubing, the bias releases an engagement mechanism which allows the anchor arrangement and the packing element to move relative to the body and thereby unset the packer. An embodiment of a dual bore packer is described. A method of well isolation is described, with an assembly including the dual bore packer. The primary bore forms the short string and a secondary bore forms the long string. By severing the short string the integrity of the long string is maintained to pull lower devices on the long string and the short string does not require tension below the packer to release.