Principal Software Developer

As a Principal Developer, you will be a senior technical authority within our defence technology community, shaping how software is designed, built, and sustained across defence services. You will provide strategic technical leadership, influencing engineering direction and ensuring that modern, secure, and sustainable development practices are embedded. You will play a key role in setting the technical vision for software engineering within defence, helping to establish a strong and consistent engineering culture. Working across delivery teams and stakeholders, you will help ensure that solutions are robust, scalable, and aligned to both user needs and the wider defence technology landscape. This role requires deep technical expertise alongside the ability to influence at scale. As a Principal Developer, you will contribute to decisions that shape platforms, patterns, and approaches, supporting the delivery of applications and services that are critical to national security. In a rapidly changing landscape, we require experienced and flexible individuals who can work in a close-knit team to use their multi-disciplinary skills to collaborate, problem-solve, and deliver within a highly assured private cloud infrastructure environment. This is a capability-focussed team, working on unique and highly specialised data and insight solutions within a modern secure facility, contributing to capabilities of national significance. For more information on the benefits of working for UKHO and the Civil Service, please see the attached candidate pack. Hybrid working This job role is based in our modern and purpose built offices based a stone's throw from the M5 in Taunton, Somerset. There will be some opportunity for hybrid working - a maximum of 1 day a week based remotely, 4 days in the office. Additional Information: Part-time hours will be considered (minimum of 29.6 per week), As a Trading Fund of the Ministry of Defence, the UKHO works hand in glove with uniformed colleagues from across the Royal Navy and other allied Defence organisations to ensure the timely and accurate provision of mission-critical data at the point of need.

• Supporting the defence development team in solving technical issues

Provide expert technical guidance to defence related development teams, resolving complex or high risk technical issues, act as the escalation point and ensure that solutions are effective, sustainable and in line with our technical direction.

• Defining and Implementing engineering standards

Lead the definition and adoption of engineering standards across the defence teams, ensuring consistency, quality and security in software delivery. Support teams to deliver these in everyday development practices.

• Working with business users to translate a user need into a design

Work with business users and stakeholders to understand user needs and operational requirements. Translate these into clear, high-level technical designs that balance user outcomes, technical constraints, and defence requirements.

• Working with other Principal Developers on a technology choice

Work with peers to assess and agree technology choices across defence services. Ensure decisions are aligned with wider technical strategy and support long-term sustainability.

• Reviewing code/designs from within the defence area

Review software code and technical designs to ensure they meet quality, security, and engineering standards. Provide constructive feedback to improve consistency, reduce risk, and support continuous improvement.

• Mentoring teams on best practice

Mentor and coach development teams on modern engineering best practices. Support capability growth across defence by sharing knowledge, encouraging effective ways of working, and fostering a strong engineering culture., When you click 'Apply now' you will be asked to attach your anonymised CV and input a 500 word supporting statement on the criteria below. Timeline:

• Advert Closes for applications: 28/05/26
• Shortlisting: w/c 08/06/26
• Interviews: w/c 22/06/26

We will try to meet the dates set out in the advert. There may be occasions when these dates change. You will be provided with sufficient notice of the confirmed dates. Sift/Shortlist Criteria: All applications are processed anonymously. You will be short-listed against the following criteria using the information provided in your supporting statement and your CV., Process:

• Single Stage Interview via TEAMS. You will be contacted to book a suitable slot if you are shortlisted (see our Candidate Pack for further information)
• Interview will be with a panel of no more than 3 people and will last approximately 1 hour and 20 minutes. During the interview, you will be required to give a 10 minute presentation as noted above. Full details of the format will be given in the invitation to interview.

Onboarding Checks In the event you are offered a role with us, you will be required to go through Basic Personnel Security Standard (BPSS) checks which will include Employment and Right to Work Checks. Security Clearance (SC) will need to be obtained prior to the role commencing. You will also need to apply for Developed Vetting (DV) which can be completed while working for us but the offer will remain conditional until DV is gained. Please see our attached Candidate Pack for further details and Terms. Please note, we are unable to offer visa sponsorship. Nationality requirements: DV - reserved This is a Ministry of Defence reserved post and open to sole UK nationals only. Successful applicants will require Developed Vetting (DV) and therefore need to have resided in the UK for a minimum of 24 consecutive months within the last 10 years. Feedback will only be provided if you attend an interview or assessment. Security Successful candidates must undergo a criminal record check.Successful candidates must meet the security requirements before they can be appointed. The level of security needed is . .People working with government assets must complete checks. Nationality requirements Open to UK nationals only. Working for the Civil Service The sets out the standards of behaviour expected of civil servants. We recruit by merit on the basis of fair and open competition, as outlined in the Civil Service Commission's .The Civil Service embraces diversity and promotes equal opportunities. As such, we run a Disability Confident Scheme (DCS) for candidates with disabilities who meet the minimum selection criteria.The Civil Service also offers a Redeployment Interview Scheme to civil servants who are at risk of redundancy, and who meet the minimum requirements for the advertised vacancy. Diversity and Inclusion The Civil Service is committed to attract, retain and invest in talent wherever it is found. To learn more please see the and the . Apply and further information This vacancy is part of the initiative.Once this job has closed, the job advert will no longer be available. You may want to save a copy for your records. Contact point for applicants

Person specification * Practical coding experience in Net and awareness of Python

• Wide range of development experience
• Practical experience of leadership of technical teams
• Up to date knowledge of modern engineering technology and tools
• Experience in defining & implementing engineering standards

Behaviours We'll assess you against these behaviours during the selection process:

• Seeing the Big Picture
• Communicating and Influencing
• Delivering at Pace

Technical skills We'll assess you against these technical skills during the selection process:

• Up to date knowledge of modern engineering technology and tools, * Practical coding experience in Net and awareness of Python
• Wide range of development experience (lead criteria), * Practical coding experience in .Net.
• Some exposure to Python (lead criteria) (assessed by a presentation)
• Wide range of development experience (assessed by a presentation)

Technical skills:

• Up to date knowledge of modern engineering technology and tools (assessed by a presentation)

Civil Service Behaviours (Grade 7 level):

• Seeing the Big Picture
• Communicating and Influencing
• Delivering at Pace

Benefits Alongside your salary of £61,605, UK Hydrographic Office contributes £17,846 towards you being a member of the Civil Service Defined Benefit Pension scheme. At the UK Hydrographic Office, it's very important to us that our people feel valued. We offer a huge range of benefits such as training and development, well-being support, flexible/ homeworking, a fantastic state of the art building, high spec equipment, and so much more. See our attached Candidate Information Pack for more details. Things you need to know Artificial intelligence Artificial intelligence can be a useful tool to support your application, however, all examples and statements provided must be truthful, factually accurate and taken directly from your own experience. Where plagiarism has been identified (presenting the ideas and experiences of others, or generated by artificial intelligence, as your own) applications may be withdrawn and internal candidates may be subject to disciplinary action. Please see our for more information on appropriate and inappropriate use. Selection process details This vacancy is using , and will assess your Behaviours, Experience and Technical skills.