suggestion

suggestion

Without having to qualify it, as in indicating the portfolio, you could say "ministerial adviser," but in the presence of additional related context ("of Culture" in your case), then the only way to say it is "adviser to the Minister of Culture":

79,600 refs for "adviser to the minister"; below are some examples that would have to be native English (not translations):

But he points out that when he took on Canada's top economic job, ... 4, 2005, as **special adviser to the minister of health** on mental health in the federal ...
www.cbc.ca/news/background/canada_us/mission_washington.htm...

McGill Reporter - Volume 28 Number 10
He has served as the president of both the Canadian Association of Orthodontists ... roles including: **senior adviser to the Minister of National Defence**, ...
reporter-archive.mcgill.ca/Rep/r2810/board.htm

From 1986 to 1989 John was an **Adviser to the Minister for Education**, before being appointed as an official of the Australian Labor Party. ...
www.health.sa.gov.au/Default.aspx?tabid=

appointed by Governor-General and is the Chief Executive of the New Zealand Defence Force and the **principal military adviser to the Minister of Defence** and ...
www.forces.gc.ca/site/Minister/eng/Comparative/susx_nz_e.ht...

1975-77, **Special Adviser to the Minister of Public Utilities and Transportation**, and Director of Advisory and Monitoring Unit, Jamaica, on Leave-without-pay ...
www.fao.org/docrep/meeting/X8515e.htm







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Note added at 15 hrs (2007-01-17 11:40:56 GMT)
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Oops! I meant to say "adviser/or" -- "advisor" is the second choice.

This might be the best option, as the links below suggest the term is used in Canada, Australia and the United Kingdom.

In February, 2005 Minister Dosanjh appointed the Honourable Michael Wilson as a Special Ministerial Advisor on mental health in the federal workplace and ...
www.hc-sc.gc.ca/ahc-asc/media/nr-cp/2005/2005_130_e.html - 19k - Cached - Similar pages

Ministerial Advisor to the Federal Minister for Aged Care Ministerial Advisor to the State Minister for Community Services ...
www.easternhealth.org.au/eastern/board.html - 22k

London Markets opened by Pakistani Prime Ministerial advisor The London Stock Exchange welcomed a senior delegation of officials from the Ministry of ...
www.londonstockexchange.com/en-gb/about/cooverview/thesourc...

Position: Ministerial Advisor on Education for Work within SECPLAN, later SETCO. Description: Strengthening the quality of national education system by ...
www.cambridgedata.com/petersijbrandij/img/sijbrandij.rtf - Similar

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Note added at 21 hrs (2007-01-17 18:19:38 GMT)
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Two good options:

Ministerial Advisor on Culture (in upper case, to refer to the specific ministry/cabinet-level department)
Advisor to the Minister of Culture (as Muriel has suggested)