Dear Khalid, in case if CHC London is sending originals then you will get a TCS, and the individual envelope named to you will be originated from Pakistan not London (Visatronix gets a bulk from London to Karachi and then sends Docs to individuals as per the address details made available by CHC London)
But if you get MR, and a letter requesting for PCC, RPRF, POF and updated forms BUT NO ORIGINALS, then you will get them through Royal Mail in a khaki color envelope (size is half of A4) and the Forms/letter will be single time folded. It will be have address of CHC London given on that. it will be via ordinary mail NO Registered Mail (meaning by no receipt of delivery) all on the mercy of Post Man.