Here is my question to a certified UK accountant and his response (feel free to decrypt it):
Question: The director of a limited company, who is a resident in another country, is he subject to the dividend tax in the UK? (the dividend tax that is applied on
dividends after the corporation tax)
Answer: The tax charge for non-residents on
investment income arising in the UK is restricted to the amount of tax, if any, deducted at source. If the tax charge is limited in this way, personal allowances will not be given against other income. This restriction does not apply in any tax year when residence is split between resident and non-resident.