I have received more information on dismantling gas holders from the council. It is the ones in Wokingham which are being dismantled now. The one in Reading opposite Newtown school on the other side of the Kennet is not being dismantled in the short term but the owner has contacted the council about this.
More detail below:
Thank you for your enquiry, received on 19th May 2015, concerning the dismantling of two Gas Holders. Having contacted SGN, who sent the letter to your constituent, I can clarify that the letter relates to the dismantling of two gas holders to the west of Suttons Park Avenue [...]. This land is actually outside of the boundary of Reading Borough Council, and is instead within Wokingham Borough Council. SGN has confirmed that they have been liaising with David Wetherill from Wokingham Borough Council’s Planning Department (0118 974 6389 or firstname.lastname@example.org and copied into this email), so I would advise your constituent to contact David for all matters concerning this particular site. SGN confirmed that they notified Wokingham of their intention to demolish these gas holders last year, with further details being available to view via Wokingham’s website (use the reference number DEM/2014/0790 to view documents submitted and the decision notice by Wokingham).
The entirely separate gas holder [...] is within Reading Borough Council (accessed via Kennet Walk). I can confirm that there are no current planning applications at this site, but in the past week a pre-application enquiry has been submitted concerning the dismantling of this holder. This is presently being considered by officers with view to providing advice to SGN. More generally, the site is allocated within the East Side Major Opportunity Area of the Reading Central Area Action Plan (2009). The specific policy reference is RC3f, with the principle allocation being as follows: “This area will be used for residential development. Development should enhance the character of the mouth of the Kennet and should maximise the potential of the site to be a river gateway to Reading”. As such, the future use of the site is earmarked for residential development. Under policy CS16 (Affordable Housing) of the Core Strategy (2008, altered 2015) 30% of the total number of dwellings would be sought to be affordable, unless viability circumstances justify a lower affordable housing contribution.
I hope that this information is of assistance to you. Should you have any questions or queries concerning the above, please do not hesitate to contact me.