Also, we saw a 3% increase to SiriusPoint premiums underwritten to $651 million from these four consolidated MGAs. Despite the strong underlying performance, the book value of our consolidated MGAs is only $90 million and we continue to believe that the actual economic value is significantly higher. I will again reemphasize that I believe the value of these MGAs is not fully reflected in SiriusPoint share price. Moving on to our reserves and our philosophy around reserving. We continue to maintain a prudent approach to reserving as evidenced by our positive prior year development in 2023. For Q4 discrete, this was $35 million for our core business and $63 million for the full year, excluding any benefits linked to the LPT. Similarly, reserve releases were positive for our consolidated business, excluding LPT at $6 million in Q4 and $46 million for the full year 2023, which includes increasing our reserve prudence by $30 million during Q4 after a strong performance year.
Our strong results coupled with the LPT we completed at half year, allowed us to further strengthen our balance sheet position as we move forward into 2024. Overall, our balance sheet is strong. Our Bermuda Solvency Capital Ratio is 237% at the end of the third quarter. Also asset and leverage has improved following the 10% growth in diluted book value per share during the fourth quarter. Growth in book value was driven by mark to market gains on the fixed income portfolio and the positive earnings generation during the quarter. Full year book value per share growth was strong at 18%. Although our capital levels are strong, the structure is not fully optimal and we are reviewing our capital instruments to make sure we operate with an efficient framework.
Our aim is to be a prudent steward of capital and we are updating our ROE guidance to 12% to 15% during the medium term. We are pleased and proud to have not only hit, but surpassed all the financial targets that we set for 2023. I am grateful to my colleagues who have pushed hard this year to create shareholder value. That said, the numbers we delivered this year are not a destination and we aim to do better. I have said before there is no complacency. As we move away from restructuring, we are focused on being a value creation company that delivers consistent profit while operating at best-in-class levels. We know this is an ambition, but one which we feel has more credibility after our strong 2023 performance. I would like to thank all our stakeholders, shareholders, customers and employees for their support and patience during a turnaround year which is never taken for granted.
We believe the future is bright at SiriusPoint and we are excited for 2024. With these remarks, I will pass it over to Steve, who will take you through the financials.
Steve Yendall: Thank you, Scott, and good morning, good afternoon, everyone. I will now take you through the financial section of the presentation starting with our full year financials on Slide 13. We had a strong year and delivered net — record net income to common shareholders of $339 million, an impressive $742 million improvement on 2022. All three sources of earnings, underwriting, MGA fee income and investments contribute positively to the results. Core underwriting results improved significantly as we delivered record underwriting profits of $250 million. The 2023 results include a one-off benefit of $105 million due to reserve redundancy linked to the lost portfolio transfer transaction, which itself demonstrates our prudent reserving philosophy.
Excluding the releases linked to the LPT, the result was still a record for us with underwriting profits of $145 million and a combined ratio of 93.7%. Our portfolio actions are having a clear impact, with catastrophe losses for the core business down 90% to $14 million and other parts of the portfolio are also improving. More detail on our reduction of underwriting volatility is available on Slide 8. Whilst our consolidated gross written premium was stable, the top line for our core business decreased 3%, reflecting the ongoing portfolio actions. Reinsurance premiums decreased by $250 million, largely due to pulling back in international property. This was partially offset by growth in the insurance and services segment which increased by $156 million.
During 2023, we took additional actions on our workers comp and cyber portfolios, which will have an impact on our 2024 premiums and offset the underlying growth in the portfolio. Capital-light net services fee income increased 37% to a record $50 million, driven by higher fees from Arcadian and IMG. Service revenues are up 10% versus last year, while service margins increased 4 points to 21% for 2023. Total investment result was strong at $273 million and driven by $284 million of net investment income, which surpassed the revised net investment income guidance of $250 million to $260 million given in the third quarter. Unrealized and realized losses including from related party investment funds were $11 million and significantly better than the $436 million loss in 2022.
