SE 4300 was a high subsonic anti-aircraft missile intended to intercept targets in the 20-30 km range. It used a liquid rocket sustainer (nitric acid + furaline) derived from the Maruca's engine giving a thrust of 540 kN. Different solutions were used for boosting the missile: a cluster of five STRIM solid motors (70 kNs each) later replaced by a SEPR 5053 motor (304 kNs) or two lateral SEPR 685 boosters (160 kNs) used in the SE 4350 variant. The guidance system used radar homing then an internal seeker.
Vehicle testing began in February 1954 at the Sahara range and interception tests started in October 1956. At the program cancellation in spring 1957, 84 SE 4300 and 41 SE 4350 had been launched of about 175 manufactured.
I was about to say "For a French missile, that looks very German".
This is what World War 2-era guided missiles look like. However, if you look at early French missiles in their own right, they too have their own particular appearance - which is different from British (e.g. Fireflash, early Folland Red Dean), Russian (AA-1 Alkali) and American (BW-0 Terrier, early Falcon, prototype Sidewinder, Sparrow I) missiles of the same basic generation.
I'm unsurprised that it was cancelled. For a missile that got axed in 1957, it looks at least 12 years older than that.