A Darracq undercover Mystery? (update: about Raylton jr.; not Railton)

The car registered X15?0 is an Armstrong-Whitworth circa 1908, this make sitting nicely with the Northumberland CC registration and Blenkinsopp Castle as above. Armstrong-Whitworth cars had the distinctive low clip-retained radiator filler cap seen here - I don't know of another make that shares this feature.

In regard to the second photo of the two cars I think the one on the left is a Napier taxi chassis of about 1910. The straight axle, fender style and short radiator filler neck match up. Also, I think the Renault has a diaper. I once visited a gentleman who is meticulous. When I got home there was a phone call. It was him asking what I thought was the best way to remove the couple of oil drops my Austin left on his driveway. You can always tell those who are meticulous by the shine on their shoes an old saying goes.

If, as Arejan and Kevin suggeste, it is a Charron, and it is wearing the Big Circular C with Ltd inscribed in it, it is probably late 1906 or 1907, since the company of Charron was only formed in 1906, but only registered in 1907 (London).
Stuart

Sometimes it can be just as interesting and revealing to look at the people involved. A quick on line search reveals that (assuming a slight spelling mistake in the article), Edward Raylton Joicey was born in 1890 so would be only 12 when the Renault was new.
His father however, Lieut-Col. Edward Joicey, was born in 1865 and I would place the gentleman in the car as closer to 37 than 12. Perhaps Edward Junior is in fact the youth proudly displaying his conquest in the second picture. They were strongly associated with both Blenkinsopp Castle in Northumberland and 22 Upper Wimpole Street, London. The architecture of Upper Wimpole Street looks remarkably similar to the initial picture so it might be worth considering these for locations that the photos were taken.
As for the Charron (and I believe Ariejan is correct here) they changed their badge around this time so those in the know should be able to tell us when the round logo seen here was used to help date the car

My guess is the bag is really just more a drape and was used to not cloud the coachwork via too many mechanicals - ie focus on it's beauty. They may have done further editing prior to publically releasing any photos.

After some thoughts and further research I want to change my id of the car on the right of the second photo. The emblem on the coal scuttle is hard to decipher, but I'm inclined to think now that it is a Charron. The other car is still under investigation!

I bet the guys wife was tired of the oil all over the shingle driveway and said " put a diaper on that thing or leave it out on the road"

The car on the first photo is a 14hp 1902 Renault tonneau. On the other photo the right car is a ca 1912 SCAR, the other (ca 1910) car is still a mystery to me. It reminds vaguely of Ariel-Simplex, but the straight I-beam front axle is unusual. A higher resolution scan to observe the radiator badge would be most welcome!

RE the unidentified cars; on the left, maybe a circa 1909 Fiat and on the right maybe a circa 1910-1912 Arrol-Johnston.