Just for clarity, here is a copy of the commands used and their output...
clive@HP-ProBook-4740s:~$ sudo -i
[sudo] password for clive:
root@HP-ProBook-4740s:~# fdisk -l
Disk /dev/sda: 698.7 GiB, 750156374016 bytes, 1465149168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: dos
Disk identifier: 0x0df34a5a
Device Boot Start End Sectors Size Id Type
/dev/sda1 * 2048 1457002495 1457000448 694.8G 83 Linux
/dev/sda2 1457004542 1465147391 8142850 3.9G 5 Extended
/dev/sda5 1457004544 1465147391 8142848 3.9G 82 Linux swap / Solaris
Partition 2 does not start on physical sector boundary.
Disk /dev/sdb: 59.6 GiB, 64016220160 bytes, 125031680 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x5acb7baf
root@HP-ProBook-4740s:~# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.27.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): d
No partition is defined yet!
Could not delete partition 140037349443457
Command (m for help): q
root@HP-ProBook-4740s:~# dd if=/dev/zero of=/dev/sdb bs=1M count=1010+0 records in
10+0 records out
10485760 bytes (10 MB, 10 MiB) copied, 1.11393 s, 9.4 MB/s
root@HP-ProBook-4740s:~# fdisk /dev/sdb
Welcome to fdisk (util-linux 2.27.1).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Device does not contain a recognised partition table.
Created a new DOS disklabel with disk identifier 0x74004536.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p):
Using default response p.
Partition number (1-4, default 1):
First sector (2048-125031679, default 2048):
Last sector, +sectors or +size{K,M,G,T,P} (2048-125031679, default 125031679):
Created a new partition 1 of type 'Linux' and of size 59.6 GiB.
Command (m for help): t
Selected partition 1
Partition type (type L to list all types): b
Changed type of partition 'Linux' to 'W95 FAT32'.
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Synching disks.
root@HP-ProBook-4740s:~# mkdosfs -F 32 -I /dev/sdb1mkfs.fat 3.0.28 (2015-05-16)
root@HP-ProBook-4740s:~# cp -Rp /home/clive/Downloads/vortexbox/BootUSB/. /media/clive/4189-9543
root@HP-ProBook-4740s:~#
This all runs fine without error.
The problem is with the commands that follow this as in my OP.