These two ships were originally designed as slightly modified "Royal Sovereign" Class battleships, but after the Falkland Islands battle, where the Battlecruisers aquitted themselves, it was decided that they should be redesigned as battlecruisers. It was intended that they be completed in 15 months, but this time was somewhat exceeded.
These two ships were extremely fast, easily topping 32 knots, due in part to their extreme length : beam ratio but this also at the expenses of light armour and construction, and although they were impecable seakeepers and good gun platforms, their light build made them shake awfully when they fired all guns at once, and Renown's first brodside trails did considerble damage, requiring hull strengthening.
The original triple 4" guns were not popular, being 3 seprerate units in a common mount, requiring 23 crew for each mount. Their great speed made them ideal for chasing ships, such as Graf Spee, which was almost reached from the other side of the world before she scuttled.
While they were identical sister-ships on completion, Renown was altered so much in her 1936-39 reconstruction that the two ships virtually became 1-ship classes. Renown's reconstruction gave her an imposing appearance, with a cliff-like tower bridge sticking up out of her full to a towering height.
Renown served throughout World War II, most notably as the heavy consort to the carrier Ark Royal in Force "H" based at Gibraltar. In 1944 she joined the Eastern Fleet, and in 1945 the East Indies Fleet.
Repulse had a relatively uneventful war career until she proceeded to the Far East in November 1941 and met her end shortly after, unescorted with Prince of Wales, Japanese carrier planes attacked and sunk both ships.
Ironically, it was the old and poorly armed and armoured Repulse that survived for longer, twisting and dodging the bombs for a full 15 minutes after Prince of Wales was sunk until she to met her fate.

1:600 HMS Renown as rebuilt. A handsome, imposing figure, she was very fast and fairly well armed with six 15" main guns. A powerful secondary battery was a feature of the rebuild, 20 4.5" guns being shipped. The original light AA armament was limited to a paltry three octuple pom-poms, less than in Repulse. The secondary director position aft was created by transferring the original director from the conning tower - the latter removed and a new director added at bridge-top. © Andrew Arthur

1:600 HMS Renown in 1944. The major changes have been adding RDF on the directors, and at the mast-heads. ( AW, SW, SB and AR types ) The aircraft and catapult have been removed and the boats moved down to the boat deck, contained in a temporary housing. This space, the former boat deck and many others have been filled by a powerful light AA armament, sixteen twin 20mm and twenty-four single 20mm Oerlikon AA guns added, and a fourth pom-pom on "B" turret. © Andrew Arthur

1:600 HMS Repulse in 1939. She carries a mixed light and heavy armament dotted around the superstructure - built up over the decades into something resembling some of Japan's "pagoda" bridges. There are triple 4" low-angle gun abreast the bridge and at the extreme of the forecastle deck, the octuple pom-poms similarly placed but one deck up. There are six single 4" AA guns, two abreast the fore-funnel at forecastle level, two abreast the after funnel on the boat deck and two abreast the after HA director - of which there are two, one fore and one aft. Quadruple half inch machine-guns are carried abreast the fore-funnel and the mainmast. The main armament is directed from the conning tower director and the range-finder on "A" turret andthe secondary triple 4" guns from rangefinders on the bridge. © Andrew Arthur

1:600 HMS Repulse at the time of her loss in 1941. Changes are limited to the addition of eight single 20mm AA, two on "X" turret, four around the after superstructure and two below the conning tower. The only other change is a new coat of paint. © Andrew Arthur