I had wrongly assumed that Andrew Vallance would not reply to my last email. However to his credit he has. First I include part of my last email to him which is relevant to his reply. If you want to check out the whole correspondence the links are   and the full FOI Request 
Cathy Fox to Andrew Vallance, (Secretary D Notice Committee)
“I shall acquiesce to your request to desist from further
correspondence, after this email. However I refute that 3 emails on
pertinent and legitimate points could be taken by any
reasonable person to be “repeated questioning that has become
burdensome and vexatious”.
My last question,
Reading the DA notice below, if an agent or officer of a secret
service mentioned in a) was a paedophile and abused children, is it
not entirely possible that there arises a conflict of interest in
that if the paedophilia was exposed, national security could be
said to be at risk and newspapers asked not to publish?
Indeed bearing in mind that paedophiles are open to blackmail, is
it not likely that agents or officers are chosen because they are
paedophiles, and are able to be “turned” to do what their bosses
and people who wield real power wish them to do?
If their bosses are in fact paedophiles, as is alleged with
Oldfield and Hayman, then the situation gets more complicated,
especially when a different secret service realises this.
This is one reason why people believe D / DA notices have been
used/misused to cover up paedophilia.
Can you state categorically that no D/DA Notice 05 has been used,
and that use has not inadvertently or deliberately covered up abuse of
DA – Notice 05: United Kingdom Security & Intelligence Services &
Information falling within the following categories is normally
regarded as being highly classified. It is requested that such
information, unless it has been the subject of an official
announcement or has been widely disclosed or discussed, should not
be published without first seeking advice:
(a) specific covert operations, sources and methods of the Security
Service, SIS and GCHQ, Defence Intelligence Units, Special Forces
and those involved with them, the application of those methods*,
including the interception of communications, and their targets;
the same applies to those engaged on counter-terrorist operations; ”
Dear Cathy Fox,
Your hypothesis below is not only completely speculative and unfounded, but also ignores the internal checks and balances within the intelligence agencies (not the least of which is the direct vetting system). These impose a constant watch for any potential security risks; they would certainly involve anyone (however exalted) involved in paedophilia.
However, the subject of this correspondence has not been the possibility of paedophiles within the intelligence agencies, but whether the D/DA Notice System has sought to suppress media reports about them. As I have repeatedly said to you, but which you seem unable to grasp, I know that in the 10 years since I have been DPBAC Secretary that that has never and could never have happened, but also – for all the reasons set out to you in my previous emails, which you seem determined to ignore – I believe it is inconceivable that any of my predecessors would have done so. Certainly, and having yet again gone through the archived files, there is not the least shred of hard evidence to support this empty conspiracy theory. I say again to you, if you or those who are making these allegations have hard evidence (not hearsay) about this issue, would they please give us copies of it, rather than making unsupported allegations or indulging in open-ended enquiries which lead nowhere? Finally, the only people who ‘believe D / DA notices have been used/misused to cover up paedophilia’ are those who are either ignorant of the facts or cannot view them objectively.
As I said in my last email, I have replied to your enquiries with full openness and transparency, save those that would breach the DPBAC code of confidentiality and thus put at risk the whole DA Notice System. The contents of your last email has only confirmed my view that your repeated questioning has indeed become vexatious, and hence this will be my last communication to you.
Andrew first dealt with my hypothesis that “if an agent or officer of a secret
service mentioned in a) was a paedophile and abused children, is it not entirely possible that there arises a conflict of interest in that if the paedophilia was exposed, national security could be said to be at risk and newspapers asked not to publish?”
I consider this to be one reasonable explanation of how part of the paedophile cover up has happened.
However Andrew not will not even contemplate that a member of the intelligence agencies can be a paedophile….”Your hypothesis is completely speculative and unfounded, but also ignores the internal checks and balances within the intelligence agencies (not the least of which is the direct vetting system). These impose a constant watch for any potential security risks; they would certainly involve anyone (however exalted) involved in paedophilia.”
Firstly I would not say that my hypothesis is completely speculative or unfounded. Peter Hayman  Maurice Oldfield  and Anthony Blunt  were paedophiles I believe. Cyril Smiths widespread paedophilia was covered up by politicians, police, special branch and MI5 . Jimmy Savile of course would have been vetted at BBC  and should have been on other occasions yet that apparently did not pick up his paedophilia. This is just the tip of the iceberg.
The Secretary of the D Notice committee will not even accept the premise of my hypothesis, and he relies on “direct vetting” and unspecified checks and balances to assume that no one in the intelligence services is a paedophile.
From this flows his conclusion regarding that a D notice could not be used to cover up an operation in which there was a paedophile agent or officer. “I know that in the 10 years since I have been DPBAC Secretary that that has never and could never have happened, but also – for all the reasons set out to you in my previous emails, which you seem determined to ignore – I believe it is inconceivable that any of my predecessors would have done so.”
There are no paedophiles in the secret services so that it could not be covered up by a D notice, it seems is the thrust of his argument. So move along, nothing to see here!
I disagree and think it is very dangerous that the Secretary for 10 years of this committee thinks so. In fact this opinion itself puts national security at risk, and explains partly why we are in the postion we are today with a paedophile network across people in power.
 2014 Dec 3 Cathy Fox A little more on D notices https://cathyfox.wordpress.com/2014/12/03/a-little-more-on-d-notices/
 Cathy Fox FOI Request https://www.whatdotheyknow.com/request/da_notices_index_and_other_infor#incoming-592453
 2014 Nov 4 NY Enquirer http://nyenquirer.uk/mi5-special-branch-prominent-paedophiles-cover-peter-jaconelli/
 2014 Nov 22 Guardian http://www.theguardian.com/society/2014/nov/22/media-gagged-westminster-child-abuse-ring
 1989 May 13 After Dark ‘Out of Bounds’, Channel Four http://youtu.be/BvAAY7UiMH8
 2012 Nov 19 rochdale Online http://www.rochdaleonline.co.uk/news-features/2/news-headlines/75362/cyril-smith-allegations-mp-danczuk-wants-mi5-coverup-inquiry
 Paul Foot Who Framed Colin Wallace ISBN-13: 978-0330314466
 Peter Wright Spycatcher ISBN-13: 978-0670820559
 2014 Nov 8 Daily Mirror http://www.mirror.co.uk/news/uk-news/mi6-chief-shamed-diplomat-raped-4596308
 2o14 Dec 1 Cathy Fox D Notices 1 https://cathyfox.wordpress.com/2014/12/01/d-notices-da-notices-don-hale-and-d-notice-committee/