As much as I love London, I must say that it's quite dreary at this time of year, so I'm glad it's only a short stop over this time.
I flew Virgin Atlantic's morning flight from Newark to London, and had two small carry-ons with me. My small Domke and a canvas laptop shoulder bag. I "linked" both with carabiners, and had them stuffed with all my photo gear as well as my Acer netbook. All my cables and electronic "support system" were in my checked-in luggage, including my 70-200mm lens.
The security check was polite, fast, efficient and thorough. My Domke bag was singled out for a quick swab by a TSA agent since it had all the gear...and within a minute, I was cleared.
On arrival, I checked my main bag and found that the TSA had opened it and left me a note saying that it had done so. My TSA-approved locks were there as I had locked them. And nothing was missing.
Efficient and professional.
The second test as to my carry-on configuration will be tonight as I check in to my Virgin flight to Delhi. I expect the lines at Heathrow's security will be long.