Rosenthal-Hornburg Group 
PO Box 320
Saines, Middlesex, TW181 XN, UK

Dear kotu-ga,

I have conducted searches on three search engines and there is little
information that I can provide.

Rosenthal-Hornburg Group is not a limited company registered in the United Kingdom.
http://wck2.companieshouse.gov.uk/ce0510193d5d914e334898d9f35e8837//wcframe?name=accessCompanyInfo

It is possible that it is a sole trader?s name but there are no databases for this.

Rosenthal-Hornburg Group is not registered with the Financial Services Authority.
http://www.fsa.gov.uk/register/

Rosenthal-Hornburg Group is not registered with the Data Protection
Act Commissioners.
http://forms.informationcommissioner.gov.uk/search.html

No telephone number listed with British Telecom.
http://www2.bt.com/edq_busnamesearch?namespace=coexistence

The address is confirmed as PO Box 320, Staines, Middlesex, TW18 1XN,  UK
http://www.royalmail.com/portal/rm

Post Office boxes can be rented at £106 a year and mail can be
forwarded to another address or collected at the sorting office.
http://www.royalmail.com/portal/rm/content2?catId=400144&mediaId=2600028


I hope this answers your question. If it does not, or the answer is
unclear, then please ask for clarification of this research before
rating the answer. I shall respond to the clarification request as
soon as I receive it.
Thank you
answerfinder

I am satisfied with the answers provided.