The double-decker bus looming out of the fog is a Yellow Coach Model 720, which was nicknamed Queen Mary in a nod to the famous Cunard superliner RMS Queen Mary, launched in 1936.

The Chicago Motor Coach Company had 100 of the Series 2 that were built in 1936, and 40 of the Series 4 (fuel tank and battery location moved to eliminate fire hazards) that were built in 1938. They proved to be very useful and many of them were rebuilt several times before finally being retired in the early 1950s. The Fifth Avenue Coach Company bought 25 Series 3 and 35 Series 5, which were the New York versions of the Series 2 and Series 4 respectively, with some body changes.

According to New York Fifth Avenue Coach Company: 1885-1960 by Oliver J. Ogden, bus Number 104 (seen in the bright sunlight below) was:

the Yellow Coach demonstrator for the new Queen Mary Design. After it was shown in New York, it kept the No. 104 but was relettered "Chicago Motor Coach." It stayed with Chicago and then was sold to Coast City Coaches of New Jersey in 1945. [Via Motor Bus Society]

Actually, it was destined for Chicago all along as it was intended to replace No. 103—the 1933 Model 706 prototype that was the basis for the Model 720 (and which, after retirement, appeared in several movies). The New York Model 720s were numbered in the 2000s. No. 104 was actually the only Series 1, built in 1934 and used in 1935 as a demonstrator on Route 5 in New York City before being sent to Chicago to be put into regular service.

Why all the swapping around? Because both the Chicago Motor Coach Company and the Fifth Avenue Coach Company were both owned by the Omnibus Corporation and shared the same paint scheme. And the Omnibus Corporation and the Yellow Truck and Coach Manufacturing Company were the brianchilds of John D. Hertz, along with Hertz automobiles, Hertz Rent-a-Car, Yellow Cab Company, etc., etc.

The Model 720 were visually similar to the Yellow Coach Model 735s, but Chicago Motor Coach Company did not acquire any Model 735s. A 1936 Series 2 is seen below.

They were so popular that kids got to get in on the action.

Save for the street furniture and bus markings, this could be London on a clear day back when everyone heated with coal. The buses' position on the street gives nothing away because they appear to be driving roughly in the middle -- a tendency toward which has not infrequently been ascribed to bus drivers on both sides of the water.