This article aims to shepherd you with professional acumen through the web of duties that you will need to fulfil in the United Kingdom.

Before we proceed, it’s important to understand the legal landscape. In the UK, the Trustee Act 2000 sets out your general duties and powers. The Inheritance Tax Act 1984 similarly looms large, demanding thorough adherence to tax management and accounting. Case law can also unfurl invaluable insights into how these principles translate in practice.

Notify Beneficiaries and Obtain Vital Documentation

Your first task is to reach out to the family and the beneficiaries to inform them of your appointment as the successor trustee. This role casts you as the touchstone of the trust's administration following the grantor's departure. Furnishing beneficiaries with copies of the Declaration of Trust becomes your duty, providing transparency in your upcoming actions.

Amidst this, obtaining certified copies of the death certificate is essential. These documents are the foundation for the legal authority you wield in the forthcoming asset management tasks.

Secure and Inventory Trust Assets

Identifying and cataloguing all assets confined within the Trust is paramount. Ensure each asset's security and stewardship, acknowledging your fiduciary duty to protect these items or properties for the beneficiaries.

Tangling with banks to gain rightful access to the grantor's accounts may be necessary. Similarly, you'll be liaising with the Department of Social Security, insurance companies, and retirement fund controllers to secure any death benefits owed.

Collaborate and Settle Financials

Act in concert with the grantor’s will executor, especially if debts or taxes are owed. The trust assets may be funnelled to address these obligations, with every expense being meticulously recorded.

Where a 'Pour-Over Will' is present, transferring lingering assets not within the Trust but assigned to it requires your attentive coordination with the executor to assure smooth conveyance into the trust fold.

Prudent Account Management

Closing unnecessary accounts, like those of credit cards and services, whilst potentially maintaining certain utility accounts to preserve asset value, entails a balancing act of prudent assessment. Ensuring insurances remain intact to safeguard the estate's worth during the transition phase also features on your to-do list.

Distribution and Fulfilment of the Trust Instructions

With profound respect for the grantor’s wishes, your task is to oversee the thoughtful distribution of property to the beneficiaries as detailed in the Declaration of Trust. Should you encounter broader instructions involving general assets or an estate sale is required, your judgement must be as fair as it is objective.

Throughout this intricate quilt of tasks, decreed by UK law and woven through with the grantor's last will, your responsibility is both a legal commitment and a personal honour. It demands attention to detail, unwavering integrity, and empathetic communication.

Finally, always be mindful of the emotional complexities this process can entail for the beneficiaries. You are their support and guide. By embodying the trust and efficiency this role necessitates, you ensure the grantor’s legacy is honoured and their beneficiaries are well cared for.

If the mantle of successor trustee has been bestowed upon you, it's crucial to heed these responsibilities with the acumen and empathy they require. Should you find yourself seeking clarity or assistance, consulting with a legal expert can always illuminate the path ahead. Remember, in the measured fulfilment of these duties lies the upholding of a last will and the protection of a legacy.