An imaged and developed element, such as a lithographic printing plate, is provided by infrared radiation imaging of a negative-working imageable element having an outermost imageable layer that includes a free radically polymerizable component, a free radical initiator composition comprising a diaryliodonium borate, and an infrared radiation absorbing compound. The imageable layer also includes a polymeric binder that is represented by the following Structure (I): -(A)w-(A′)w′-  (I) wherein A represents recurring units comprising a pendant reactive vinyl group, A′ represents recurring units other than those represented by A, w is from about 1 to about 70 mol %, and w′ is from about 30 to about 99 mol %. The imagewise exposed element is developed with a gum to remove only the non-exposed regions. The gum has a pH greater than 7 and up to about 11 and at least 1 weight % of an anionic surfactant.