Nothing now remains of old Lathom House and no picture of it is known to exist. Its situation and appearance was accurately described by Seacome, but it is impossible now even to identify the site.[124] Lathom House in those days was strong not only from its situation but from its structure. It stood upon marshy ground in a hollow surrounded by small hills which made it very difficult to effect an approach to the walls. The wall itself was six feet thick, and the whole was surrounded by a moat twenty-four feet across and six feet deep; a palisade between the walls and the water provided a further defence. On the wall were nine towers upon each of which were planted six guns, three turned one way and three the other, and in the centre of the building was a higher tower called the Eagle Tower. The gate house, which was a strong and lofty building, stood at the entrance to the first court.
On Saturday, February 24, 1644, it was decided at a meeting of the Committee at Manchester that Colonels Assheton, Rigby and Moore should undertake the siege of Lathom House.[125] News of this came to Lathom on Sunday, and the Countess of Derby at once sent out to obtain information from a friend which she had in the enemy's camp, while hastening on the reinforcement and provisioning of the garrison. The messenger returned on the following day with the news that the Parliamentarian troops had already marched as far as Bolton, Wigan and Standish. On Tuesday, February 27, they had taken up their quarters round the house at a distance of from one to three miles from it. The rest of the week was spent in negotiations. A formal summons of surrender was first brought on Wednesday by Captain Markland from Sir Thomas Fairfax, who further promised that he would use his influence with Parliament if the Earl of Derby would submit himself to their mercy. Lady Derby asked for a week's delay in which she might send a message to the Earl to know his opinion. This was refused, and Fairfax then requested her to come in her coach to New Park, a house about a quarter of a mile from Lathom, in order to have a personal interview with himself and his Colonels. But the Countess remembering her birth, returned a haughty refusal, "conceiving it more knightly that Sir Thomas Fairfax should wait upon her than she upon him." After two more days of messages Assheton and Rigby entered Lathom with propositions, which as might have been expected were severe. The House and all arms and ammunition were to be delivered up, the garrison having leave to depart to Chester or elsewhere; Lady Derby was to reside at Knowsley, being allowed 20 musketeers for her protection, or she was to join the Earl in the Isle of Man. These conditions were refused "as in part dishonourable in part uncertain." On Monday, March 4, Assheton came again alone in order to receive the royalist proposals. These required a month's delay for the removal of Lady Derby and her family to the Isle of Man, during which time the royalist garrison was to be kept at Lathom; but afterwards none of the arms were to be employed against the Parliament. After her departure none of the tenants of the Earl were to be molested. It was evident, however, that all negotiations were useless. On their own confession the royalists did not believe that Fairfax's promises were genuine, nor did they intend to keep their own. The Parliament referred to in their proposals was understood by them to mean the King's Parliament at Oxford. The only object of allowing negotiations at all was in order to gain time to put the House into a better state for defence. The besiegers, however, made one final offer which was brought by Colonel Morgan, the assistant engineer, "a little man short and peremptory";[126] they allowed the time which had been asked for to evacuate Lathom, but the cannon were to be left for its defence and not removed with the rest of the arms and goods. By 10 o'clock the following day all the royalist garrison was to be disbanded and 40 Parliament soldiers to be received as a guard. The royalists, however, seeing that there was now no more time to be gained, formally broke off all negotiations. The defiant answer was at length given which had been kept in the background for a week. The Countess of Derby refused all their articles, and declared "That though a woman and a stranger, divorced from her friends, and robbed of her estate, she was ready to receive their utmost violence trusting in God both for protection and deliverance."