The maintenance and decommissioning of nuclear reactors requires the rapid cutting and welding of thick-walled pipework, to which laser processing is highly suited. However, the large size and stand-off of current laser heads precludes their use in space constrained areas and incorporation into in-bore processing tools. To address this, novel miniaturised fibre-fed laser cutting and welding heads have been designed which are capable of being used within a 90 mm internal diameter pipe. Here we will present details on the optical design of the processing heads, on-board gas systems and operating parameters. Prototype processing heads have been built and trialled at a high-power laser facility. Power transmission testing and beam profilometry confirmed the prototype heads produced suitable laser spots for processing and found the power limit for the design. During the trials, the prototypes successfully produced full-depth cuts and full penetration welds in 90 mm internal diameter, 5 mm wall pipes. Additionally, the trials demonstrated the gas cooling in the processing heads was able to provide good thermal management up to 2.4 kW. Further optimisation of the welding parameters is required, however the results presented here demonstrated the feasibility of using this novel miniaturised optics design for in-bore laser cutting and welding of pipes.