Eileen Gibb was the author of a series of books featuring 'The Adventures of Sammy the Shunter' which were published by Ian Allan in a small, oblong format similar to the railway stories of the Reverend W. Awdry, whose 'Thomas the Tank Engine' the series closely resembled. Very closely. The stories were still being reprinted in the 1970s.
For Robin, Eileen Gibb wrote stories featuring a new character called 'Tubby the Odd-Job Engine' which starred another Thomas look-alike. The series, launched in the first issue (28 March 1954) was illustrated for many years by Arthur W. Baldwin who had been associated with the Sammy the Shunter books. After a year or so, the short Tubby yarns began alternating with other characters ('Tracey the Tug Boat', 'Basil Bus Stop', etc.) but continued to appear until volume 14 when the series took on a wider focus and became 'Honeytown Tales', still featuring Tubby but also giving more space to other inhabitants of Honeytown. I've yet to establish when the series ended.
But what of Eileen Gibb? I've been unable to find anything else by her beyond the stories mentioned above, the books below, and a number of contributions to Robin Annual (3-8, 1955-60). The few records that remain relating to Robin seem to indicate that Eileen Gibb may have been the pen-name of one E. Holder (perhaps Eileen and perhaps a married name? perhaps a married daughter?), although later stories, published in the 1960s, were by actor Donald Bissett.
The Adventures of Sammy the Shunter:
__1 Sammy Gets Streamlined. London, Ian Allan, Dec 1949.
__2 Sammy Goes to the Circus. London, Ian Allan, Sep 1950.
__3 Sammy Goes to Sea. 1951?
__4 Sammy Goes to America. London, Ian Allan, Nov 1951.
__5 Sammy Goes to Fairyland. London, Ian Allan, Aug 1952.
__6 Sammy Meets Father Christmas, illus. Arthur W. Baldwin. London, Ian Allan, Nov 1952.
__7 Sammy and the Old Engines. London, Ian Allan, Jun 1954.
__8 Sammy Joins the Scouts. London, Ian Allan, Jun 1955.
__9 Sammy Goes to the Pole, 1957?
__Sammy the Shunter Bumper Book, illus. Jack Atkins. London, Ian Allan, Oct 1954.
Billy the Bus series:
__1 Billy and the Robbers, illus. Arthur W. Baldwin. Hampton Court, Surrey, Ian Allan, Feb 1953.
__2 Billy Goes Exploring. London, Ian Allan, May 1953.
Sammy Rhymes series:
__1 Sammy Goes to School. London, Ian Allan, Jul 1953.
__2 Sammy Sees the Doctor. London, Ian Allan, Feb 1954.
Tubby the Odd-Job Engine, illus. Jill Franksen. London, Hulton Press, 1959.
Sammy Saves a Railway Line, illus. Jack Atkins. London, Ian Allan, 1965.
My Trains Book. London, Ian Allan, 1953 (contains 'The Holiday Train' and 'Sammy on the Christmas Tree' by Eileen Gibb).
(The Sammy the Shunter covers I grabbed from a recent eBay sale. Tubby the Odd-Job Engine is from Robin Annual 5 (1957) and is © Look and Learn Magazine Ltd.)