Create a new Site-to-Site VPN connection. Set the transit gateway as the target gateway. Enable acceleration on the new Site-to-Site VPN connection. Update the VPN device in the London office with the new connection details.

Modify the existing Site-to-Site VPN connection by setting the transit gateway as the target gateway. Enable acceleration on the existing Site-to-Site VPN connection.

Create a new transit gateway in the eu-west-2 (London) Region. Peer the new transit gateway with the existing transit gateway. Modify the existing Site-to-Site VPN connection by setting the new transit gateway as the target gateway.

Create a new AWS Global Accelerator standard accelerator that has an endpoint of the Site-to-Site VPN connection. Update the VPN device in the London office with the new connection details.