Acccess the VM after using the VPN
Using the GDS VPN
Using Cisco AnyConnect will prevent traffic to *.dev.gov.uk from the host (i.e. your machine) reaching the guest (i.e. the VM).
After disconnecting from the VPN, the routing can be restored using the following:
mac$ sudo ipconfig vboxnet0 delete 10.1.1.1 mac$ sudo ipconfig set vboxnet0 manual 10.1.1.1