A bit of information if you are planning on going to Tibet it can only be done via an authorised agency. I did all my own bookings via online sites and knowing what I know now I suspect there are only a handful of authorised agencies. There are bucket loads of websites offering tours but once you get into it does not take long to realise that they are all similar and most maybe various re-skins of the same authorised agency. Bob mentioned that the travel agencies have little or nothing to do with the drivers or the guides. From what I understand Bob, the driver and all other guides have their own licenses, I had picked up on this as Bob mentioned the agencies provide little or no information to travellers about what is expected. He had been explaining that he knew a guide that was currently under investigation and could potentially loose their licence as one of the guests was wearing a tee-shirt which the Chinese did not like but this type of information had not been sent to the guests in advance.
The travel permit, you need one and it can only be collected in China and you cannot damage it. To get on the fight to Lhasa it must be the original, mine was checked before I was allowed through airport security, when it is checked it is not just a once over, it seemed like it was checked and read in detail and your passport is also checked. On boarding the aircraft it is checked again. On arrival in Lhasa the driver was waiting and he wanted to check it, at the hotel it is checked again as is your passport. On leaving Lhasa for the first time which was the first time the group was together, Bob collected everyones permits and held onto them until the day of departure. On the day of departure Bob gave back a photo copy of the permit he said the original document had to be returned and could not taken with us. He said that the copy would be checked on departure but it was ours to keep. On the train, the police came through and checked it to make sure you had not over stayed the travel period.
Passports, it is strongly advised that you carry it with you at all times, which is also a general recommendation when in China. In Lhasa there didn't seem to be to many restrictions on where you could go but in saying that this it may be difficult of enter some of the sites with out your guide. Out side of Lhasa I think you are meant to stay with your guide, I like to wander around and in most cases there were no issues. I was pulled up and my passport checked in Shigatse.
One thing I had mentioned was at the Potala Place a few questions had been asked about Dalai Lama's1-4 which was initially brushed off. At the Tashilhunpo Monastery I had asked what were the differences between the Panchen Lamas and the Dalai Lamas'. Bob didn't respond and I thought he had not heard me and asked a similar question, the Taiwanese girl spoke to me and said that the group next to ours were all Chinese Officials and it is best not to ask questions like that.
The police and military presence is heavy and on day one I had been advised do not take their photo or talk to them unless required. Moving through the different regions Bob had to register the group and in the Shigatse area there was a physical police check point we had to pass through and Bob was answering the questions. When you are taking photos of sites the police will just turn away or try and move out of the way.