The object struck one of the horses pulling the carriage and only the skill of the carriage driver saved the situation. The second, younger horse, sensing something was wrong, reared up and struck procession steward Gus McDonald who was sent flying and was badly bruised.

The incident took place as the procession made its way along the town's North Street.

Although the incident left Eilidh startled, she didn't let it spoil her day.

Eilidh, of Woodlands Drive, said: "Something made the horse jump and it was frightening. I didn't know what it was and I couldn't see anything.

"But it was still a good day and I enjoyed it."

Mum Marie said: "Apparently a stone was thrown from one of the houses at the horse. We didn't see anything from where we were standing but the horse reared up.It was quite traumatic for Eilidh, because she's only 12 years old.

"But it didn't spoil the day and I was glad that there was nobody seriously hurt."

Jeff Stewart, executive chairman of the fair committee, warned that a decision would have to be made on whether to continue using
carriages after this incident.

He condemned the unknown perpetrator's action and added: "It was an idiotic and irresponsible act which could have had much more serious implications.

"Fortunately, the carriage driver was able to control the horses, but Queen Eilidh and the page boys got quite a fright while Gus McDonald was knocked to the ground and was quite badly bruised. I can't understand why anyone would do such a thing."

One eyewitness said: "This incident scared many people and our young queen was visibly shaken and reduced to tears."

A spokeswoman for Central Scotland Police told the Journal and Gazette that officers had been aware that the Queen's carriage was involved in an incident but that no complaint had been received and, consequently, there had been no investigation.

In a separate incident, a snare drum which was a prop at an arch in St John's Way was stolen.

The householder said: "This heartless person ruined my son's fair day."
The officer in charge of policing in Bo'ness has praised the public after the fair passed with very few problems for officers.

Despite the large crowds, only three people were charged with alcohol-related incidents.

Chief Inspector Gary Lawrie, Grangemouth and Bo'ness sub-area commander, said: "We fully recognise the importance of the fair to the people of Bo'ness.

"I am delighted that the number of incidents that occurred was so small and this was down to the co-operation from the people of Bo'ness as well as the police presence in the town to prevent any incidents from occurring."