Upvote:0
Probably. You can't count on it though...
As you have an Indian passport, a valid US visa, and are in transit between the US and India, you qualify for the 'Transit without visa' concession (click to expand the section on that page for details). Under that concession, you will be able to do a landside transit of up to 24 hours between your flights.
However, as warned at the bottom of that page:
Please note that this concession is operated at the UK Border Agency's discretion. Our officers may therefore prevent you from using the concession. If you are unsure whether you meet the concession's criteria, you should get a visa before you travel.
So, they may not allow you to enter the UK, and you may be required to spend the whole time airside within the airport. I don't know how common that is, but be prepared to show evidence of why you will return to the airport to catch the onward flight in case you're challenged!