Gasright - I don't know anything specific about BG, but can only give you advice from my perspecives & experiences as both interviewee and interviewer.
1.
Be punctual & on time. Sounds obvious, but you'll be surprised how many people turn up late for an interview ! If for any reason (roadworks, unforsee road accident, car breaking down, whatever) always have the phone number with you of the person you're meeting and always phone in plenty of time to let them know - its called courtesy, and no-one gets "marked down" for being courteous in my experiences.
2.
Be smart & professional. Don't chew gum (seen it) don't come into the interview room eating a burger saying that you were hungry (seen that too !) Turn your mobile OFF whilst being interviewed. If its a suit and tie job, get it right - if a dark suit & dark shoes then white socks only go to prove you're colour blind !
3.
Be informed. As another poster has already replied, do your homework about what BG is, who they are, what their corporate & customer service aims are. These days with the internet its so easy, hence there's just no excuse for not doing it, unless you really don't want the job & aren't interested ..... in which case save your time & skip the interview altogether.
4.
Ask questions. Stay away from negative questions like "How much holiday do I get", "Do you pay sick pay", "How much notice do you require when leaving" ...[yep, you've guessed it,, I've heard ALL these from interviewees !!] Ask positive questions : "What are the prospects for promotion", " What does BG do to support personal & professional development " as well as near the end the (excellent) suggestion from another poster about why does the interviewer work for BG and what keeps them there !
Most Importantly : Having asked a question, actively LISTEN to the answer. There is no surer way for an interviewer to check if you're really interested & actively participating than to ask a question based on an answer you gave 5 mins ago ....
If you are a nervous type of person and feel intimidated when being interviewed, try to relax. Smile & sit upright. If there's more than 1 person asking you questions, look towards each person when you answer them, not into your lap or 'off into space'.
Try to answer each question immediately without thinking about it and starting the answer with an 'er' or an 'um'. Rolling your eyes upwards slightly (or looking up to the right, eyebrows raised) before answering is a bit of a giveaway that you may be
making up a bit of the answer.
If you don't know - then say you don't know, but show interest by asking the interviewer to explain the question and try to get a mini-conversation about that specific question started. This proves that you can engage with people and are not an introvert.
Above all- go in to the interview with a positive frame of mind as if you are going into something which you REALLY ENJOY. Sounds a bit daft, but it can make a lot of difference. People like people who are relaxed, smiling & confident (but not over-confident & comatose
)
Let us know how you get on.
Have a look under Google for BG and print off the info you find, then read it offline when you'll not be disturbed
Good luck !