Following deregulation of the bus industry in 1986, Howle applied to operate route 16 between Hamstead and Birmingham in competition with West Midlands Travel.

[3] In March 2008, Go West Midlands was sold to Rotala, who also owned Central Connect and North Birmingham Busways.

[4][5] Rotala originally kept the Diamond business separate from Central Connect and Ludlows (purchased later[6]), instead switching a number of routes between the three operators.

First Midland Red subsequently sold both its Redditch and Kidderminster depots to Diamond Bus.

Route 202 Halesowen - Bromsgrove and 4H Hayley Green - West Bromwich used Royale Black Diamond buses.

[10] On 28 July 2017, the business of Hanson's Local Buses, which operated services in Stourbridge, Dudley and surrounding areas, was purchased.

On 7 June 2010, Central Connect launched the Signature brand with two Solihull routes that were taken over from National Express West Midlands, the S2 (S2/S2A/S2C) and S3 were operated with Optare Solo SRs with leather seating and on-board WiFi.

On 26 July 2010, the Signature brand took over route 82 from National Express Coventry but following a more direct route between Solihull and Coventry using Mercedes-Benz Citaros and service S4 (taken over from Grosvenor) using MCV Evolutions, again both feature leather seating and free on-board WiFi.

On 27 March 2011, the Signature brand expanded again with the addition of route 30 Solihull-Acocks Green which was withdrawn by National Express West Midlands.

Following loss of many contracts and reorganisation of bus routes in the Solihull area, the Signature brand was dropped in 2019.

As part of a working partnership with Worcestershire County Council, a new fleet of Red Diamond bus services were introduced to operate in Redditch.

These buses are mainly Diamond-owned Wright Eclipse bodied Volvo B7RLEs but there have been several repainted Dennis Darts in operation.

A month later on 25 February 2007, Diamond also withdrew the evening services on route 246 between Redditch and Evesham due to low passenger numbers.

In February 2009, Red Diamond won Worcestershire County Council contracts to operate a number of services around Droitwich and Redditch starting in April 2009.

[20] Droitwich residents were unhappy about the changes, showing concern about losing the known and respected drivers from the local routes, however, Diamond Bus entered into an agreement with the former operator of the routes, allowing them to continue operating with the same drivers, while Diamond Bus provide the buses and uniforms.

[21] In 2010, amid much criticism of the poor performance of the existing buses from Worcestershire County Council and passengers, Diamond brought nine MCV Evolutions for services 362, 363 and 382.

In October 2006, the business was purchased by Rotala subsidiary Flights Hallmark, and although the original plan was to transfer the assets and operations to Flights Hallmark, contract issues necessitated the continuation of the Zak's legal entity, the company being renamed Central Connect Limited in April 2007.

[29] A number of routes, however, were transferred to National Express West Midlands due to the expiration of the tenders operated on behalf of TfWM.