US Customs at Heathrow?

No. See: http://www.cbp.gov/border-security/ports-entry/operations/preclearance

There was a trial about 25 years ago, but the higgledy-piggledy nature of Heathrow is not really suitable. When it is finally sorted out into a straight toast-rack around 2035 maybe. I may also depend if the airlines want to pay for it since it has little benefit for the airport.

If you want pre-clearance fly via Dublin as you did before.

Thank you all for the responses.

Don't give up hope for preclearance at Heathrow--at least at some terminals. According to the Skift travel website, US authorities are considering expanding preclearance to 10 airports: Brussels Airport, Belgium; Punta Cana Airport, Dominican Republic; Narita International Airport, Japan; Amsterdam Airport Schipol, Netherlands; Oslo Airport, Norway; Madrid-Barajas Airport, Spain; Stockholm Arlanda Airport, Sweden; Istanbul Ataturk Airport, Turkey; and London Heathrow Airport and Manchester Airport, United Kingdom. No word on when this may happen.

Advantage of preclearance is shortening your connection time if you have a connection back in the States. I.e. not having to go thorough US CBP immigration check upon arriving at your transfer airport and having to retrieve and recheck baggage after going through US CBP customs.

The distinct disadvantage of a Heathrow preclearance would be lengthening your connection time at Heathrow. In addition to the potential long walk (run) between terminals when connection to a flight back to the states, you would have to go through US CBP immigration, customs and security before heading to your flight back to the States.

If it comes to missing a flight because of an immigration check point, is it better or worse) to miss your once a day transatlantic flight or your domestic US flight back to your hometown?