Use references to investigate how a senior engineer worked over time, especially the questions that remain after interviews. Ask for specific situations, establish what the referee observed and connect the answer to the role. A familiar name or an enthusiastic endorsement is not enough on its own.
Employment verification and a detailed reference conversation serve different purposes. Verification may confirm dates and role. A reference can add evidence about technical decisions, collaboration and response to difficulty, depending on what the referee is able to share.
Start with the technical leadership mandate or engineering brief. The questions should follow the work you need, not a generic checklist of whether someone was liked.
Decide what you still need to understand
Write down the unresolved questions from the hiring process before contacting anyone. Perhaps the candidate described leading a migration, but you need to understand how they handled disagreement. Perhaps their individual delivery is clear and you want evidence of helping others become effective.
Separate missing evidence from a negative assumption. “We have not explored their work during an incident” is a useful question. “They probably struggle under pressure” is already a conclusion that could distort the conversation.
Choose a small number of themes and use the same core questions for comparable candidates. Leave room to follow a relevant example, but avoid letting an engaging story take the discussion far from the role.
A reference should complement the interview record. It should not become a final informal vote that silently overrides a structured assessment.
Agree who can be contacted and when
Ask the candidate to suggest people who can speak directly to the relevant work. A former manager, senior peer, cross-functional partner or direct report may each have a different view.
Get explicit agreement before contacting anyone, including people found through your own network. Confirm timing as well as names. Contacting a current employer without permission can expose a search the candidate intended to keep private.
If you want another perspective beyond the supplied referees, explain the gap and ask the candidate to agree an appropriate person. Avoid a vague request to “ask around”, which makes it difficult to control relevance, accuracy or confidentiality.
Permission to contact a referee is an operational safeguard. It does not replace the employer’s separate responsibility to identify the appropriate legal basis for processing recruitment information. UK data protection guidance covers candidate and referee information throughout recruitment. [Source 1]
Establish the referee’s vantage point
Begin by confirming the working relationship, the period involved and how closely they observed the candidate’s work. Ask which projects or responsibilities they shared.
A manager who reviewed outcomes once a month sees something different from an engineer who paired with the candidate daily. Both can be useful, but their answers should not be treated as the same kind of evidence.
Explain the new role briefly and say which areas you want to explore. Give enough context to make the questions meaningful without sharing unnecessary information from the candidate’s interviews.
Verify that the person is who they say they are through a reasonable professional route. Keep that check proportionate and record it alongside the relationship information.
Ask about technical ownership
Technical ownership is clearest in decisions and consequences. Ask the referee to choose a piece of work they observed, then investigate the candidate’s contribution within it.
Useful questions include:
- What part of the problem did this person own?
- Which decision did they make with incomplete information?
- What alternatives did they consider, and what constraint mattered most?
- How did they test or monitor whether the decision worked?
- What did they do when the original approach needed to change?
Follow up on the sequence rather than collecting adjectives. If the answer is “excellent technically”, ask for a specific example that illustrates that judgement.
For a founding engineer, explore how they moved from an unclear need to a useful first version. For a senior specialist, focus on the depth relevant to the mandate.
Ask how they made other people more effective
A senior engineer’s effect on the team often extends beyond their own output. Explore how they handled review, disagreement, context and shared responsibility.
Ask for an example of a decision where another person disagreed with them. What did the candidate do to understand the disagreement? How was the decision resolved? What happened to the working relationship afterwards?
Ask how they helped a less experienced colleague or a new joiner. Look for specific practices such as explaining constraints, making a system understandable or leaving useful documentation, rather than equating support with always being available.
For leadership roles, ask what the team could do more independently because of this person’s work. This can reveal whether their contribution increased capacity or made them the permanent bottleneck.
Explore difficult work without inviting gossip
A useful difficulty question stays close to the job. Ask about a missed commitment, an incident or a technical approach that did not work, and what the candidate did next.
Ask what support or context would help them succeed in the proposed role. That produces a more actionable answer than requesting their “biggest weakness” without context.
If the referee raises a concern, ask whether they observed it directly and for a relevant example. Distinguish a pattern from one event and record the context. Do not ask for private health, family or other irrelevant personal information.
UK guidance says references supplied by employers must be fair and accurate. Acas also explains that opinions should have supporting evidence and irrelevant personal information should not be included. [Sources 2 and 3]
Interpret green and red signals carefully
A strong reference connects the person’s actions to observable outcomes and explains the conditions in which they worked well. It can include limitations without undermining an otherwise positive assessment.
A concern worth investigating is a specific, relevant account that conflicts materially with the candidate’s description. Clarify the difference and give the candidate a fair opportunity to address it before making a decision based on disputed information.
A brief factual reference, a refusal to comment or an unavailable manager is not automatically a negative signal. Employer policies can restrict what referees provide. UK guidance recognises that references may be limited to basic details. [Source 2]
Likewise, hesitation is not a reliable code to decode. Ask a neutral clarification instead of inferring a hidden meaning from tone or a pause.
Keep UK and US checks in their proper scope
Recruitment records should contain information relevant to the decision, with appropriate access, retention and transparency. Avoid storing a sprawling transcript when a clear factual summary will do. The ICO’s recruitment guidance addresses how candidate information is handled; its current page is marked for review following legislative changes. [Source 1]
In the US, federal anti-discrimination obligations apply when employers use background information. If a business uses a background-reporting company, the Fair Credit Reporting Act can add requirements including written permission and prescribed steps before an adverse decision based on the report. A direct reference call and a purchased background report are not automatically the same process. State and local rules also need checking for the role. [Source 4]
Agree the process with the person responsible for compliance before checks begin. Do not improvise more intrusive checks because a candidate has reached the final stage.
Make an evidence-based decision and close the loop
Summarise each conversation under the original themes. Record direct observations, the referee’s opinions and any unresolved contradiction separately. Include the relationship and date so later readers understand the context.
Compare the reference evidence with interviews and work samples. If a concern matters to the role, resolve it deliberately. If it does not, do not let it become an unexplained reason for rejection.
Use relevant findings to improve onboarding as well as selection. A clear description of the environment in which someone does their best work can help their manager set expectations and support them from the start.
The first five engineering hires guide can help place that support in the wider team plan. Done well, references add detail to a hiring decision that already has a clear purpose. They do not replace it with reputation.
If you are planning a technical hire, Start a conversation.
Legal and tax points are summaries; take professional advice.
Sources
- Employment practices: recruitment and selection, ICO, checked 31 October 2026. The page identifies the guidance as under review following the Data (Use and Access) Act.
- References: your rights, GOV.UK, checked 31 October 2026.
- What employers can say in a reference, Acas, checked 31 October 2026.
- Background checks: what employers need to know, joint FTC and EEOC guidance, checked 31 October 2026.
The question bank and evidence-review method are Corellia Talent’s recommendations.