UK visa with I-797 Notice of Action

[econair]

I am an Indian national and plan to travel from the US to India for my extension H1-B stamping at Mumbai. (I currently have an expired H1-B visa stamp on the passport, but the extension H1-B has been approved by USCIS.) On my return journey from India to the US, my travel route is via London. I wish to have a stopover in London for a few days, for which I understand that I would need a UK visitor visa.
My question is regarding obtaining the UK visitor visa from the consulate in LA, using the H1-B approval notice as a supporting document. Has anybody had experience with applying for a UK visitor visa while having only an approval notice to show for US legal status as opposed to a valid visa stamp on the passport?
Any help or suggestions would be appreciated.
Thanks

[txh1b]

Your legal status in terms of valid approval of extension is sufficient.

[johnfarnsworth]

The British High Commission in LA should not really be fazed by this - your situation is actually quite common.

[jinesh25]

Hi econair,

Did you get your UK visitor visa with only I797 ? I am in the same boat and planning to apply for UK visitor visa in NY. Mine visa on passport is expired but have a valid I797 approved. Plz reply..

Thanks