This is what happened to me. I lived between villages and got picked up by the bus from the other village. 4 boys very badly picked on my for weeks starting verbally and ending up with punches and strangling.
It ended when the teachers found out about it, the boys were suspended for a week and afterwards I was left alone, even ended up getting on fairly well with one of them a long time afterwards.
I'd advise getting your son to talk to his form tutor in the first instance about the issue. Secondary school is an odd time between child/adult and if he can resolve this himself then he's learning a life lesson. If he doesn't feel able to or anything escalates then it's time for parental support.
My parents were at no time involved with the school over my bullying and I didn't tell them about it at the time, although I have great and supportive parents. I guess I was embarrassed and I'm glad your son is not the type to be embarrassed enough to keep quiet.
Good on him for standing his ground! He's already sent a clear message to the other child - "I ain't being pushed around by you!". The other boy has tried saving face by having a pop at him on the way home - here's the advice - DO NOT, UNDER ANY CIRCUMSTANCES
A) RISE TO IT B) CRY
Give it til Friday. Any more crap, speak to the form tutor but don't wade in tomorrow...he has to cope with tossy kids and you can't fight them all for him but you can assure him, you are there for back-up if it gets too much. The ones that seem gobby at first often turn out to land themselves in the crap with even older kids soon enough and that regulates them considerably!
My son aged 11 started secondary school 2 weeks ago. He wasn't at our local primary school so although he is going to the secondary school in our catchment area he doesn't know any of the children. He has to catch the bus but he goes with our neighbour's son who has also just started there. I would say he is finding it quite hard to settle in but we are trying to be positive and have explained that it will probably take a while.
Today he has come home and told me that a boy (also a new starter in year 7) told him to "get out of his seat" this morning on the bus. He didn't and told the boy he could sit where he liked. The boy found another seat but then started making fun of him on the journey home. My son was quite upset tonight. We have told him to tell us if this boy does anything similar tomorrow as I am afraid he has already picked our son as his target. My question really is do I call the school tomorrow anyway and ask to discuss this incident with someone or do we leave it a few days? I feel terrible for my son. He is such a lovely, sweet boy but quite a young and naive 11 year old. He will undoubtedly face more idiots like this boy on the bus but I'm scared this could escalate.