U.K. Visitor visa on a German National D visa valid for 6 months

Hi,
I am looking to apply a U.K. Tourist (Standard Visitor) visa.

I am an Indian national currently working in Germany since 15 Sep 2017. I am on a National D visa valid for 6 months starting 14 Sep 2017 till 13 Mar 2018.

Previously I was staying in UK on a tier 2 General work permit until 14 Sep 3017.

Could you please advise if I will be allowed to submit an application on my current National D visa valid till 13 Nar 2018.

Or do I need to wait to get the Blue Card or the Residence permit and then only I can apply .

Thanks in advance
Satya

Since UK is a different country (and not member of Schengen), having a national visa for Germany (or the Schengen area) does not help at all in getting a UK visa.