http://www.channel4.com/producers-handbook/c4guidelines/social-media-guidelines
Policy on Online Postings including Twitter

This policy applies to all independent production companies
working on any Channel 4 programme and any talent appearing on
a Channel 4 programme who are making online postings on sites
such as Twitter, Facebook and other forms of social networks. It
also applies to all staff working on the production. Adherence to
this policy should be considered part of all relevant contractual
agreements for individual programmes and developments, as well
as being referenced in contracts with staff and talent.

All information relating to the Channel's output is confidential,
unless agreed in advance with the commissioning editor of the
programme.

Only staff specifically permitted and agreed with the
commissioning editor, should make comments on Twitter or other
sites about specific information related to a programme.

Once permission to post online has been granted to named
individuals, the tenor and the subject matter of any postings
should be consistent with that of the programme they are working
on. Any significant departure should be raised with the
commissioning editor at Channel 4.

All postings should also comply with the rules and principles set
out in the Committee of Advertising Practice (CAP) Code and the
Consumer Protection from Unfair Trading Regulations (2008). In
particular should anyone to whom this policy applies promote a
product or service in exchange for free or discounted gifts or cash
or any other benefit in kind they must ensure that they are fully
transparent about the nature of the relationship with the product
or service. In the case of Twitter they must use "#ad" or "#spon" in
the tweet itself to make it clear that there has been a reciprocal
arrangement in place and therefore the tweet is effectively a
marketing communication. In the case of other social media
platforms, the same issue of transparency is relevant and suitable
words should be used to make the reciprocal arrangement clear to
readers. If in doubt please ensure that you err on the side of
caution and are transparent.
Please bear in mind the following principles:

If you are thinking of setting up a dedicated social media account
for a programme, you must discuss this with Channel 4 first.
Proposals must be sent to Channel 4 via
[email protected]; you will be contacted back within 2
weeks. If you are planning to use social media solely for casting or
researching your programme, please discuss this with your
commissioning contact instead; and if it goes ahead, please send
the link to [email protected].
There are broadly two types of online posting, both of which
are subject to this policy:
1. Postings on designated Channel 4 websites / accounts - In such
cases the rule is that postings are subject to Channel 4's normal
editorial standards and controls, such as standards of due
impartiality, editorial independence and accuracy.
2. Postings on personal websites / accounts - Where the posting is to a
personal page or account and where you are individually responsible
for the content and not legally subject to the editorial control of
Channel 4, but you must abide by the policy above.
Privacy

Colleagues should be able to communicate openly at work without
fearing that their actions or comments will be later disclosed on
the internet. For example, unless appropriate consents have been
obtained, avoid posting details of private conversations in the
workplace or meetings about the programme.
Due Impartiality

Due impartiality on political issues is a fundamental standard and
applies to all factual programming. This means for example, that
news and current affairs journalists working on this output do not
as a rule agree or disagree with a political party or politician, or
take a fixed stance on politically contentious issues. Presenters
and reporters generally should be particularly careful about
comments on political issues and politicians.

On Channel 4 designated sites, due impartiality on political issues
must be applied.

On personal sites, where you identify yourself as working for
Channel 4 output, you should avoid making statements that could
be perceived as taking a position on a political issue of the day
and it may be appropriate to place a disclaimer underlining that
your comments are personal opinion. If your profile is such that
you are likely to be identified as working for Channel 4 or any of
its services, seek guidance if you are considering posting
statements on matters of political or public controversy.
Ethical and professional conduct

Behaviour that is inappropriate at work is usually not appropriate
on the internet. On Channel 4 designated sites and sites where
you identify yourself as a person working on C4 output, avoid
abusive or aggressive behaviour and respond to others in a
professional manner.
Confidentiality

Information gained whilst working for Channel factual output is
confidential and should not be made public unless agreed with the
commissioning editor. This includes matters such as details of
confidential editorial operations, scheduling forthcoming special
projects or programmes not yet announced; details of internal
company issues, internal memos or commercially sensitive
information.
Legal responsibility

Channel 4 is only legally responsible for content on designated
websites or accounts. In such cases, Channel 4 retains final
editorial control.

Comments made on personal sites or accounts are your own legal
responsibility. Where on a personal site you are referring to
Channel 4 matters, the normal Channel 4 editorial standards and
controls should apply. You should be aware that the laws of libel
are in principle the same online as any other form of publication
or broadcast. Care should be taken when linking to sites or
republishing content that contain defamatory statements.

Care should also be taken in the light of any right to replies which
may be in the process of being sent and answered.

You should consult with your designated lawyer for clarification
on any issue relating to the timing of agreed online postings.

You should also avoid publishing material which allied to material
already available online may identify someone. This is called
‘jigsaw identification’ and can lead to libel proceedings.
Disclaimer

If there is a risk that the opinions published could be viewed as
those of Channel 4, it is usually appropriate to post a disclaimer
e.g. "These comments are my personal views and opinions, not
the views or opinions of Channel 4".
Consultation

Where a posting raises legal or compliance issues, speak to your
commissioning editor and lawyer.
Complaints/Press Enquiries

If you receive a legal complaint or a request to take material
down, or a press enquiry, following any online posting you must
immediately refer it to your commissioning editor and lawyer.