On returning to England officers and men received a vote of thanks for their heroic conduct on that occasion, passed by both Houses of Parliament. In 1867 he was selected to take command of her Majesty's forces on the disputed islands of San Juan, British Columbia, for the protection of British settlers (it being a joint military occupation with troops of the United States of America), which command he held until the garrison was withdrawn in November, 1872. During the occupation Civil Law was withdrawn, and the administration of the Government devolved upon Colonel Delacombe. Whilst holding this command he was recommended by the Secretaries of State for Foreign Affairs and for the Colonies for the local rank of Lieutenant-Colonel, for promotion by the Governor of British Columbia and the Commander-in-Chief of the Pacific, and received the thanks of her Majesty's Minister at Washington, likewise two addresses from the inhabitants of the islands. On his return to England, in 1873, he received the thanks of her Majesty's Government from the Secretary of State for Foreign Affairs; the "appreciation of her Majesty's Government of the manner the joint occupation had been conducted," from the Secretary of State for War; the "satisfaction of the Lords Commissioners of the Admiralty," and a copy of a letter from the late Commander-in-Chief of the Pacific, Sir Arthur Farquhar, K.C.B., to the Admiralty, "trusting their Lordships would be pleased to give this Officer some mark of their approval of his high services." After which he was recommended both for promotion and for the most distinguished order of St. Michael and St. George. Major Delacombe was appointed to command the Derby recruiting district in 1874. In 1876, he was in a position to retire from the service as a Lieutenant Colonel, having completed 27 years' continuous service.

On 12 March 1876 he was selected out of 72 candidates, as Chief Constable of Derby. The list of ten names of candidates for the office was reduced to six, namely:

The Council (as an elarged Watch Committee) met in the Grand Jury room, at twelve o'clock, and having before them the six candidates, and put such questions to them, through the Mayor as were deemed necessary, the election was then proceeded with on the principle of the exhaustive ballot. The voting papers having been handed round, the following was the result of the voting in three stages:

The three lowest having been struck out, the second voting was as follows:

Captain Irwin was then struck out, and the final voting was as follows:

The Mayor then declared Major Delacombe elected; and this having been confirmed by the Watch Committee, he was called into the room and informed by His Worship of his success, when he returned thanks for the honour conferred upon him. Since which time he has received the appreciation and thanks of the late Prime Minister, the present Prime Minister, and His Royal Highness the Prince of Wales, who were pleased to approve of his "excellent arrangements," whilst escorting them during their respective passages through Derby on the occasion of Her Majesty's State visit to Derby, May, 1891. Colonel Delacombe received special command from Windsor to head and lead her Majesty's procession through the town. At a special meeting of the Town Council, shortly after the event, the Mayor (Sir Alfred Haslam) referred to the Chief Constable's letter reporting his arrangements for this occasion, and he deemed it so valuable that he took the liberty of writing to Sir Henry Ponsonby to inquire if he thought the Queen would like to read the letter, and received a reply in the affirmative; the letter was therefore shown to her Majesty, and he has since been informed that it gave her the greatest possible pleasure to read the statement it contained'"

Colonel Delacombe, from the moment he took up his present position, has been indefatigable in his endeavours to look after the interests and welfare of his men.

Shortly after taking charge he obtained for them the boon of eight hours' duty instead of ten, believing ten hours to be too long for men to walk the streets and do their duty efficiently, which change has been found most beneficial to the men and to the public service, and has been now almost universally adopted.

Another change he effected immediately was in substituting for the old-fashioned uniform a useful, but at the same time smart-looking-dress which (while at first being looked upon with misgiving and spoken of as the military element creeping in) has become the established uniform of almost all large towns.

At the general meeting of all the Chief Constables of Boroughs in 1881 to consider what steps should be taken relative to super-annuation, he was elected, in his absence, as the first chairman of the Super-annuation Amendment Committee.

In 1886 he was elected president of the Borough Chief Constables' Association. During the passing of the Police Bill of 1890, when the late Sir George Campbell and Captain Verney were opposing the Bill clause by clause, he was in daily attendance at the House of Commons, consulting and giving information on the subject to various members.

In 1879 he recommended a long service scale of pay for his Force to the Watch Committee, which met with much opposition in the Council, but, after several special meetings and long discussions, was adopted by them, and ultimately approved by the Home Secretary. The scale has been found to work well, and give general satisfaction.

The result of Colonel Delacombe's example and his untiring devotion to duty has been a stimulus to the whole Force, Officers and men alike feeling that they have a most worthy and trusty chief, and one upon whom they can always rely whenever difficulties may arise. Lieutenant-Colonel Delacombe retired, owing to ill-health, as Chief Constable for Derby after 22 years on 24 March 1898