Ok....according the Caner 1994 history book...
The first nine holes were in existence by 1893, but there is no concrete record of designer. The course was modified every year for the first 4 years of ECC's existence, and had between 9 and 11 holes each year. By 1895, the 9 holes was situated almost exactly where the front nine is today. There is no record of who layed out this original nine, but it was likely a team effort among the founders. The 3rd green of the current course was a green on the original layout. Willie Campbell was the club professional in 1895 only, but there is no mention of his involvement in course planning.
In 1896, Tom Bendelow spent the golf season as an assistant professional. According to Caner, "he had a hand in building the greens, and possibly in designing the course." This was the first course that made use of the current first tee.
Upon the acquiring of the hilly property that is the centerpiece of today's back nine, the first Essex 18 was planned and opened by a Vardon exhibition in 1900. According to Caner "The architect is not recorded, but Herbert Leeds, creator of the Myopia course, John Duncan Dunn, and Walter J. Travis may all have been involved." This course was 5722 yards long. All of the holes at this time were located on the current golf course land, but some holes went in opposite directions, and there were holes across the hill in the middle of today's back nine that currently do not exist. On this course, the holes on today's front nine served as the back nine. Two holes on this course today exist in their general entirety, the 13th and 16th (original 18 #5 and #8), two holes from the original course no longer exist altogether, and fourteen other holes from the original 18 were replaced by Ross wholly or in part.
In 1908, Donald Ross was brought by George Willett from Oakley to redesign the course, then shortly after to be the club's pro. From 1910 to 1917, Ross totally redesigned the course hole-by-hole, one at a time. The Ross course that Francis Ouimet opened in 1917 played the current holes in this order: 1-16-17-18-10-11-12-13-14 (front 9), then 15-2-3-4-5-6-7-8-9 (back 9). New creations by Ross include the current 2nd, 4th, 5th, 6th, 7th, the combination of two old holes to form the current 8th, a new green at the current 9th, the great 11th, a new green and fronting hazard at the current 15th, and the current 18th. The other holes not mentioned above are not attributable to the previous designers, as they simply followed the same land as a previous hole. All were rebunkered and recountoured as Ross saw fit. Amazingly, member play continued unabated during the entire transition. During this transition time, Horace Hutchinson visited with C. B. MacDonald to play the course, and remarked that the transitions were "all the makings of a good thing."
The course layout was reordered in 1924 to today's sequence to bring both 9s to start and finish near the clubhouse. Ross had numerous bunkers in his layout, and many have been removed over the years for ease of maintenance. Not to worry, however, as the most prominent hazards from his course still exist.
Skip Wogan was Ross's caddie at Oakley (named for his penchant for skipping between balls he was shagging on the range), and his apprentice at Essex. Wogan also accompanied Ross to Pinehurst each winter to work from 1907-1916. He took over as head pro at ECC from Ross in 1913, a position in which he served until his death in 1957. Ross was only the head professional at Essex for 5 years, although he continued to work on the course as an architect until its opening in 1917. Wogan lived for 50 years in a house near the 6th tee of today's course in a house he bought from the famed George Willett. Wogan was the jack-of-all-trades professional, overseeing course maintenance, clubmaking, and tennis court and building maintenance. Skip also found time to found the NEPGA in 1920, and to create a new club tournament scoring system that is widely used today. His only actual golf course design contributions to the Essex course were the construction of the current 17th green in 1936, as the tough-to-maintain old one was build directly on ledge rock, behind today's green. He also raised Ross's current 9th green about 10 feet, and re-leveled the 12th green.
Phil Wogan took over for his father as the caretaker of the golf course in 1957, and kept the place in tip-top shape until he left the club to persue golf course design himself. Phil oversaw the addition of fairway irrigation in 1958, which replaced the old system that was above-ground in the woods adjacent to most holes. The greens were not watered with an irrigation system until much later. Phil Wogan also no-doubt tinkered with a few tees and bunkers here and there as needed.
The history as explained above does not give much credit to Skip Wogan for re-designing much of Ross's Essex course. I will say his stewardship for 44 years as golf operations head was very valuable, and important credit can be given for that. After all those years being synonymous with the club, it was certainly possible that anything Essex was believed to have been a Skip Wogan originated idea!
Interesting questions are raised in the above narrative concerning the involvement of Leeds, J. D. Dunn, and Travis. Unfortunately no documentation was available as of the writing of Caner's history. I would guess that their involvement would only have been advisory, as the early evolution of the courses at Essex seem to have a history of in-house "design." Whatever their involvement, they current course is truly Ross with a few very minor modifications by Wogan, and some inevitable greens committee tinkering.
C & W list Ross as the major architect, then redesigns by both Skip and Phil Wogan. I think these redesign attributions are a bit heavy, as most revisions by the Wogans seem to be merely improvements due to maintenance ease or course fairness.
Anyone interested in a hole-by-hole architectural history? There is a quite detailed description of each hole's history in the Caner book...