A BUS had to be taken out of service for almost a week when “mindless” students at a top-performing Mersey grammar school staged an egg and flour fight.

Last night Merseytravel, which subsidises the school travel, warned that bus companies may be reluctant to continue to offer such services if the “deplorable” behaviour from pupils at Calday Grange Grammar School continued.

The culprits struck on two school buses taking them home as they celebrated the last day of school before embarking on their GCSE exams this summer.

While the vehicle made its way from the West Kirby school, an egg and flour fight broke out, leaving the Happy Al’s bus caked in egg and flour.

The vehicle was left in such a state it had to be steam-cleaned and taken out of service for nearly a week.

The school was also billed for the mess and disruption – which the Daily Post understands was around £1,000.

Another bus, run by operator First, was only slightly affected, with sticky egg and flour residue on a small area of the vehicle needing to be cleaned overnight.

The school has written to parents condemning what it described as “a small but constant stream of complaints relating to the poor behaviour of pupils when travelling on school buses”.

And parents have been warned that the school “will consider the sanction of barring students” from using the buses after school for set periods of time revealing the misbehaviour had left other pupils fearful of travelling.

The school’s hard stance was last night welcomed by Merseytravel, which stressed that only a minority of children using its services behaved inappropriately.