The 1899 reference in the Moniteur d'Horticulture which gives the parentage of 'Maman Cochet' as a seedling of Catherine Mermet by an unknown (name lost) pollen parent is very interesting. The parentage of 'Maman Cochet' is always given as 'Marie van Houtte' x 'Mme Lambard' but in reality the references are exceptionally silent until the 1936 Rosenlexikon reference (unless there are earlier references I haven't seen). There is a report in the Rosenzeitung just before 'Maman Cochet' was released which makes comparisons to 'Catherine Mermet' without directly stating they might be related. The other interesting fact is that in the same article in the Moniteur d'Horticulture (that gives the parentage from Mermet) they state that the English Rose Society classes 'Maman Cochet' and 'August Comte' as synonyms. The French writer declares the two roses are in fact different and speculate that it is the English weather that keeps 'August Comte' paler, like 'Maman Cochet'. They also give 'Auguste Comte's' parentage as 'Marie van Houtte' x 'Mme. Lambard'.
I do wonder if someone compiling parentages back then saw the National Rose Society's listing of 'Maman Cochet' and 'Auguste Comte' as being the same and then assuming that they were identical, by extension, gave the parentage of 'Auguste Comte' to 'Maman Cochet'.
The 1911 list of compiled rose parentages by Mr Robert Daniels published in 'The Garden' does not include a listing of 'Maman Cochet', but does give 'Auguste Comte' with its usual pedigree.

It would be interesting to hear from anyone who grows both 'Catherine Mermet' and 'Maman Cochet' and if they can discern any similarities that might support this supposed parentage.

Here's the original French passage plus my translation:

Cette superbe rose est issue d'un semis de Catherine Mermet, qui avait été fécondé par une variété dont le nom à malheureusement été égaré pendant la maturité de la graine.

This superb rose is the result of a seedling of Catherine Mermet, which had been fertilised by a variety whose name was unfortunately lost during the ripening of the seed.

I guess it could also be read as as (Catherine Mermet x unknown) x unknown, but I do read it as Catherine Mermet x unknown.

This rose is undoubtedly very tough. I found one growing in the middle of a paddock in a rural area where there was evidence that a farmhouse existed there many years ago. Only a few tough garden plants remained, including a couple of peach trees and this rose. I believe it may have been planted as a kind of hedge along the front of the house originally, as it is now forming a huge clump. During the worst of the drought it died back considerably, but would still flower reliably. I decided to take cuttings on my last visit, as it is undoubtedly an extremely hardy rose. The flowers were also very vibrant and eye-catching.
At times this rose seems to have more characteristics of a HT than a classic tea rose. Even the flowers when they first open are rather HT-like. But they soon start to ruffle and it is not hard to see that they are indeed the flowers of a tea rose. The "confused mid-petals" (as Margaret Furness puts it) are also a character trait of this rose.
The leaves sometimes look closer to a HT as well, except when the new growth comes out, fairly large, red and droopy, so typical of tea roses.