Casual Dining Group is one of the largest independent restaurant companies in the UK. They operate some of the most recognisable and loved restaurant brands to be found anywhere in the eating-out market, such as Bella Italia, Café Rouge, La Tasca and Las Iguanas.

Casual Dining Group operate almost 300 restaurant sites in a variety of locations including leisure parks, shopping centres, airports and on the high street. CDG is a national business, with restaurants located across the country, from Aberdeen to Plymouth, employing more than 10,000 people and serving more than 20 million meals each year. With the strong demand for leading mid-market dining brands, they are currently opening one new restaurant every seven to ten days.

Casual Dining Group

The Situation

As part of CDG’s IT strategy to move to cloud technology, the 25sevenIT team (25SevenIT was acquired in 2018 by Timico) recommended migrating all users and over 50 mail-enabled domains to a new email platform, Microsoft Office 365.

The migration required completion of a cross-domain user migration at the same time as introducing single sign-on capability for Active Directory accounts to Office 365.

When introducing a new Active Directory domain, interconnectivity by design is built between the new AD structure and the Office 365 platform. In this scenario, however, all user accounts and mailboxes remained resident in the legacy domain, as a starting point. No tools were available to complete a seamless user/mailbox migration cross-domain, and to the Office 365 platform at the same time, therefore a solution had to be devised.

Furthermore, existing CDG business processes relied on the legacy domain and its Exchange integrations with various lines of business applications. In order to maintain business continuity throughout the migration, a solution was required to re-engineer business processes around the mail and user moves.

Further advances were sought to reduce risk to the on-premise provision of IT services, supporting the overall design and cloud strategy.

Legacy Microsoft Exchange services, that remained in place as part of the initial project, were identified as being a point of failure due to their location on-premise at CDG HQ. For this reason, further advances were required in migrating all Exchange services, service accounts, and email connectors to the cloud platform; as well as migrating all user and service authentication entry points to a cloud-first service.

Exchange connectors and user authentication will normally route via on-premise services in a hybrid scenario, therefore placing a reliance for core services on-premise at a customer HQ. The challenge here was to remove that single point of failure from the default design.

The solution required creation of a hybrid deployment that maintained the existing user experience for users attached to either the legacy or new Active Directory domain. User profiles, mail profiles and mail integrations were reset or removed during the standard migration process. Hence, a process had to be developed to migrate these elements alongside the user accounts.

The standard migration technique employed by Microsoft at this time, in this scenario, assumed mail integrations and mail profiles would be recreated individually for each endpoint. In a large organisation, such as CDG, this is not viable and the direction from the CDG management team was to retain current user experience while completing the migration, without impacting user access or uptime.

Issues such as mail delivery supporting core business processes, mail delivery across both platforms from a single distribution list, type ahead within the mail client for recent contacts and calendar sharing were all features unavailable, by design, until the migration was fully completed for all users and systems to Office 365. For a long-term project, such as at CDG, these issues had to be solved during the migration phase.

Further information

Services provided:




"The 25sevenIT team has been taking care of our IT needs for several years. Their knowledge of the technologies we need to run our business is paramount, as is the expertise they bring to the table. Recently, 25sevenIT advised us on moving to the cloud and managed the seamless migration to a cloud subscription model on the Microsoft Azure platform. This not only saves us a considerable amount of money but adds resilience and flexibility to our infrastructure and allows us to work remotely. They take the time to understand our long and short-term business goals and we are very fortunate to partner with them and be able to trust that our technology is in safe hands."

The Solution

User Profile migration technique

The solution developed a new technique to migrate user profiles and maintain user experience within the domain account and the mail client. DOS batch processes were built upon to complete user profile file transfers from source to target, with the appropriate translation for all path variables.

Mail migration technique

In order to maintain mail flow into the legacy Exchange environment (supporting legacy users who had not yet been migrated) and co-exist with the Office 365 platform, an investigation was completed into background attributes used as part of a standard user migration to Office 365 when using Microsoft mail migration tools. PowerShell scripts were developed to generate and/or update exchange attributes on the Office 365 platform for migrated accounts.

This had the effect of enabling inbound mail to be routed into the legacy Exchange environment and then seamlessly forwarded into the subset of migrated users now on Office 365. Reply and outbound messages also had to be considered for routing options and sender address labels.

Further work required was to design and deploy primary secure authentication services on the cloud utilising federation services, to include a cloud-based user directory service and remove the focus for the on-premise hybrid services around user authentication, mail delivery and line of business workflows that rely on those core functions.

All systems data maps were required to be analysed and worked through a change method for system interface connectivity, user authentication and data flow. The processes and data flows are specific to the customer business and infrastructure, therefore the 25sevenIT team worked within a project framework, including a proof of concept phase, to build, deploy and test the changes.

A process was developed to migrate domain accounts cross domain forests, while simultaneously connecting users via ADFS to the Office 365 mailbox platform for single sign-on capability. The process was further developed to support business processes that relied on mail integrations as those objects moved across the domain divide and to the cloud platform.

The Result

A seamless Office365 migration which enabled CDG to take advantage of the inherent reliability, security and stability of cloud resources and maintain functionality for line of business applications and workflows that relied on those services.