The Marquess of Bath, Ceawlin Thynn, recently backed legal action to ensure that the son he shares with his wife, Emma Thynn, who was born via surrogacy, can inherit part of his £157 million family fortune, bringing a discreet but pressing issue surrounding succession and modern parenthood into sharper public focus. While aristocratic inheritance disputes are rarefied territory, the underlying legal questions apply far beyond the landed estate.

As the use of IVF and surrogacy increases across the UK, UHNW-specialist lawyers are encountering more families facing rigid, often centuries-old legal frameworks, since inheritance law has not evolved at the pace of modern medicine.

Legal parenthood at birth

Jemma Hotta, partner at Oury Clark, explains the position in England and Wales: “In England and Wales, the surrogate will be the legal mother of the child at birth. If the surrogate is married, then their spouse will be the child’s father.”

For intended parents, particularly those who have invested emotionally and financially in a carefully planned surrogacy journey, that starting point can feel counterintuitive. Yet UK law does not prioritise genetics or private agreements at birth; instead, gestation and marital status are key factors.

The inheritance consequences are not symmetrical. Hotta continues: “If the surrogate (and potentially their spouse) does not have a will, the child will automatically be entitled to inherit a portion of the surrogate’s estate (provided their estate is large enough). However, the opposite is true for the intended parents. The child will not be entitled to inherit a portion of its intended parent’s estate unless and until a parental order is obtained.”

For families with substantial business interests, investment portfolios, property holdings or trust structures, that distinction is critical. In legal terms, a child born through surrogacy may have an automatic entitlement in relation to the surrogate’s intestate estate while holding no entitlement at all to the intended parents’ wealth until further steps are taken.

The importance of a parental order

The mechanism that resolves this imbalance is a parental order. Hotta outlines the process: “A parental order needs to be made in favour of the intended parents. This process involves an application to court and takes between 9 and 15 months to complete post-birth. Once a parental order has been made, this permanently ends the child’s legal relationship with the surrogate, and legal parenthood is assigned to the child’s legal parents.”

That timeline matters. A period of up to 15 months can elapse before legal parenthood is fully transferred and, during that window, vulnerabilities in succession planning may be exposed. As things currently stand, it isn’t possible for families to forward plan, as matters can’t be formalised in advance of the child’s birth. As Hotta makes clear: “A parental order can only be applied for after the child is born. There is no pre-birth legal process in England and Wales, and courts are not bound by a surrogacy agreement.”

For high-net-worth families, the absence of a pre-birth mechanism creates a certain vulnerability that must be factored into estate planning. If an intended parent were to die before a parental order is granted, the child’s position under the will or under intestacy rules could be uncertain, particularly where documents have not been updated to reflect the anticipated arrival.

Reviewing wills and historic trusts

Modern wills and trusts tend to reflect contemporary drafting practice. As Hotta notes: “In modern-day wills and trusts, a reference to your ‘children’ includes legitimate, illegitimate and adopted children (unless the will or trust expressly states otherwise).”

However, many substantial estates remain governed by historic instruments that were drafted in a different legal and social era. Hotta cautions: “Before 1950, adopted children were not within the definition of the adopter’s ‘children’. Historic trusts should therefore be considered to ensure that children born via surrogacy fall within the definition of potential beneficiaries.”

This point is particularly relevant for families with long-established trusts, landed estates or multi-generational structures, where capital and income pass through defined classes of beneficiaries. If the governing document contains narrow or outdated definitions, a child born via surrogacy may not automatically fall within scope.

A comprehensive review of existing wills, trust deeds and letters of wishes is advised for any family in these circumstances and, where necessary, amendments can ensure that future children, however conceived, are clearly included within their family succession plans.

Overseas arrangements and UK recognition

Many intended parents pursue surrogacy arrangements overseas, often in jurisdictions where contractual frameworks are more developed and processes appear more streamlined. Yet recognition in the UK is not automatic.

Hotta explains: “Surrogacy agreements are commonplace overseas. However, they are not legally binding in the UK. Intended parents need advice from an immigration lawyer to make sure they can bring their child back to the UK and from a family lawyer to assist with the application for a parental order.”

For internationally mobile families, this introduces another layer of complexity. Immigration status, nationality and domicile can all intersect with tax planning and succession structures. A failure to secure appropriate advice at an early stage can delay legal recognition of parenthood and, in turn, complicate inheritance planning.

In practice, experts advise getting all ducks in a row, as it were, across family law, private client, tax and immigration disciplines. Surrogacy is rarely a standalone legal event and intersects with wider wealth structuring decisions that may already span multiple jurisdictions.

The limits of peerage reform

In aristocratic families like the Baths, succession is governed not only by private documents but by the law of peerage. Reform has been debated, but progress has so far been limited.

Hotta observes: “Over the last decade, there have been multiple iterations of bills proposed to vary peerage law, be that to eliminate gender discrimination in the inheritance of hereditary titles or to include children born via surrogacy. However, they have all failed to pass due to lack of time and disagreements on the impact of existing titles. I therefore think that it is unlikely that peerage law is likely to change in the short-to-medium term, despite the rising use of IVF and surrogacy generally.”

For now, it seems statutory reform might be some distance away, leaving families reliant on careful private planning rather than legislative change. However, all eyes will be on the outcome of the Cator & Ors v Thynn & Anor [2026] case. Watch this space.

Read more: How HNWs should be preparing for 2026 inheritance tax changes