I'm not sure how WHBM comes to "the Comet 4 production was split between Hatfield and Chester as well, by when it was apparent it was well outclassed by the 707/DC8, and in the end only about 80 frames were produced, well within the capability of one of the plants alone".
What seems to be missing from that statement is any reference to the production rate which can be, and was, important if the real orders we had were to be met.
ETA Oh and the actual production numbers were 29 Srs 4, 18 Srs 4B and 28 Srs 4C plus 49 Nimrod MR1 so "about 80" should be 75 or 124 depending on how you think of things.
As a former Hatfield man I will say that Chester had a reputation as the best production site in the de Havilland enterprise and one of the best in the industry as a whole. Airbus wing production didn't go there by accident.