Hi Gareth -
I don't know of a collector's or reference website for the opaque glass made by Northwood. The popularity of their carnival glass far outpaces their other production. But maybe Glen will know of a site
I did find 2 pieces for sale on the web - Deep Cupped Bowl
and a Chinese Coral bowl with a black attached foot.
I looked in my reference books (Colors in Cambridge Glass) and confirmed that Cambridge did not make an orange-red opaque glass.
As to it being Fenton, again the Fenton Mandarin Red looks very similar in overall color until you compare the secondary color swirled in it. While Northwood Chinese Coral is red with orange swirls, Fenton Mandarin red is red with a darker red swirled in it. It is easy to confuse the 2 colors unless you have 1 of each in front of you. I have some pieces which I know absolutely to be Fenton Mandarin Red because of the mould - Big Cookies Jar and a Big Cookies Basket. No other company made pieces remotely similar to these. I also have a Northwood Chinese Coral candlestick (which again is packed away)
So from your pictures I would say this is not Fenton Mandarin Red.
Now to further complicate things, I revisited the Dugan/Diamond book I had cited previously and found another bowl that they identify as being by Diamond and similar to Northwood's Chinese Coral color. They go on to say others are similar to Fenton Flame (my first guess on your bowl before I saw your other pictures). Apparently Diamond was having problems with consistency in color.
Some of the glass artists here can probably explain this better than I, but these red colors are extremely heat sensitive and hard to produce consistently. The color differeniation seen in Fenton Mandarin Red is achieved by leaving an old gather on the punty rod then getting a new gather, so they had glass that had been heated once (which in Fenton's case is the darker color) then the overall red which was the new gather.
Here is an example of Fenton Mandarin Red
which shows the color variation fairly accurately.
Almost all the better known American glassmakers of the 1920s-30s were making these rolled rim or cupped bowls. But from the color, I would say it was made by either Northwood or Diamond if it is American. To differentiate between the 2 you would have to find bowls from each company and compare the measurements or the details of the foot or collar base. The problem with the reference books is that most picture these bowls on a stand so that you can't see the details of the foot!