Flight information prior to departure

[jmruitenberg]

Hi!

I was on a BA flight last weekend from Johannesburg to Heathrow. When we were taxiing to the runway we suddenly drove back towards the terminal. There was an announcement about that we needed to wait because there was something wrong with info that wasn't send. immediately after this announcement we went to the runway and took off. Does someone know what kind of info it could have been? IS about passengers for U.K immigration. I forgot to ask the crew.

Thanks

Joost