Soliciting Letters of Support

Hi.
Does anyone have an experience of successfully soliciting recommendation letters ("letters of support") from British institutions to apply for an endorsement from Arts Council UK? Is it worth writing "cold" emails asking to look at my portfolio and sign a letter, or does it work only through connections? Do you perhaps know anyone who can introduce me to something like Design Council UK?

For example, a friend of mine was getting an O2 visa in the USA (it's quite similar to the British Tier 1 ET), and his lawyers arranged his membership in the Art Directors Club USA. Have you heard of something like that in the UK?

The thing is, I'm quite alright in the "Additional Evidence" (won major international creativity awards, was interviewed by Adweek, etc., etc., but unfortunately I don't know anyone in British cultural organizations)

Thank you in advance,
Victor.