Maximilien was the eldest son of Jean Messervy, Seigneur of La Hougue, Constable of St Saviour, and Sara de Carteret (sister of Jurat Francois de Carteret, Seigneur of La Hague) and grandson of Aaron Messervy, Lieut-Governor.
He was born in St Saviour on 25 July 1616. His father died in 1634, and on coming of age in 1637 he inherited the Fiefs of La Hougue, Patter, es Verrants, and Petit Rozel, which were heavily encumbered with debt. According to a statement made to the Privy Council in 1640, "his father and grandfather died deeply indebted to divers persons in the isle, which debts petitioner has in most part discharged". To do this he sold La Hougue in 1638 to Jean Le Hardy.
In 1639, by the help of a bribed maidservant, he carried off to Normandy an heiress of 17, Collette, daughter of Jurat Benjamin de La Cloche, Seigneur of Longueville. He married her at St Lo.
On his return he sued Amice de Carteret, Seigneur of Trinity, calling on him "to demolish a mill lately erected contrary to law to the great prejudice of petitioner, who holds the Mill of Ponterrin". The case was taken to the Privy Council, where de Carteret pleaded that as Lieut-Bailiff he could not leave the island. How the matter ended is not recorded.
In 1640 Messervy was again appealing to the Privy Council. Some of his father's creditors refused "to take either houses, lands, wheat or money rentes at the usual rate, and do now with eagerness and extremity prosecute him to make a general cession of his estate of purpose to make a prey thereof to the perpetual infamy of his family".
Sir Philippe de Carteret, his wife's uncle, backed him up in this, and by his influence he obtained an order compelling the creditors to accept the rentes he offered.
Unfortunately he now discovered too easy a way of escaping from financial difficulties. He became an exceedingly skilful coiner. Later, when some of his coins were submitted to goldsmiths of the City of London, they declared them to be "the most artificial counterfeiting of silver that they ever saw".
In October 1640 Sir Philippe was forced to arrest him and his brother Francois for passing counterfeit Spanish pistoles and pieces of eight. Maximilien pleaded that he had received them from a Norman to whom he had sold some horses, but when his house was searched, "the melting pot, mould, metals sophisticated with false silver and gold were found in his study, which I myself saw".
The case caused great scandal, for the young men were related to the best families in the island and, after eight months imprisonment in Mont Orgueil, friends managed to secure for them the King's Pardon on 28 June 1641.
On his release Maximilien again found himself in financial difficulties. He sold Petit Rozel to Jean Le Hardy and es-Verrants to Thomas Poingdestre, Rector of St Saviour, and then lapsed with Francois into:
- "His old trade of coining false gold and vending it in Normandy and the island. Sir Philip upon proof thereof sent officers to apprehend them, but they escaped by night in a small boat into France, and not long after into England. Upon these coiners' arrival at London they, siding with Sir Philip's opposites, complained of great injuries he had done them for their good affection to Parliament".
Prynne, the Puritan lawyer, who had been befriended by Sir Philippe when he was a prisoner in Mont Orgueil, heard of this, and informed the Close Committee of their character. He wrote:
- "I employed one to find out their lodging, which he did at last, informing me that they were full of money, and that Maximilian had offered a small ingot of gold. Whereupon, conceiving that they had set up their coining trade, I procured a warrant from Justice Hooker to search their lodgings, which was delivered to Master Stone, a constable of St Clement, who, standing at their door, heard them telling money on the table; after which, he knocking at the door, Maximilian offered to escape out of a garret window, but at last they were both apprehended".
In Maximilien's trunk a mould was found and implements for coining, and in a room above, some counterfeit coins "so cunningly sophisticated with alchemy salts that they spewed like silver".
Politics at this time did not hesitate to interfere with justice, and Messervy, by appealing to political friends, nearly turned the tables on the forces of law, and almost got Justice Hooker arrested as a Royalist for issuing a warrant against him. But Prynne again intervened, and the two coiners were committed to the Gatehouse to await the next Sessions.
But before this time came, Lydcot's expedition to Jersey was planned and their friends urged so strongly the help that their local influence would give, that they were released to accompany it. This Maximilien did, though his brother remained in England. In Jersey Maximilien distinguished himself by the violence of his advice, urging that Mont Orgueil should be stormed, even though it meant the loss of 500 men.
When after three months Lydcot and most of the Parliamentary leaders fled, Maximilien remained, perhaps presuming on the fact that George Carteret, the new Governor, was his cousin. But in March 1644 Captain Carteret had him again arrested for coining. Whether this was a new charge, or the old one from which he had previously fled, is not clear. He was kept in prison until 2 August 1645, when he was brought up before the Royal Commissioners, and condemned to be hanged.
The sentence was carried out the same day. His body was handed to Thomas Poingdestre, Rector of St Saviour, who buried it in St Saviour's churchyard, and became the guardian of his two children, Philippe, aged 4, who became Deputy-Vicomte, and Sara, aged 2.