Race Comment Explainer

Original comment with matches highlighted:

held up in 4th, lost a place in rear, pushed along and d off in 4f out,

Matched phrases & meanings

Phrase	Meaning
Pushed along	The jockey started to urge the horse (hand-riding, not necessarily using the whip).
tailed off	A definitive statement that the horse was finished and effectively out of the race
Outpaced	Could not keep up with faster horses mid-race.
Held up	Intentionally raced patiently at the back to save energy.
halfway	The horse was patiently ridden up to the middle point
Rear	Running near the back of the field.

Summary

The jockey started to urge the horse (hand-riding, not necessarily using the whip).
A definitive statement that the horse was finished and effectively out of the race
Could not keep up with faster horses mid-race.
Intentionally raced patiently at the back to save energy.
The horse was patiently ridden up to the middle point
Running near the back of the field.