The returning Pat Sanderson, Miles Benjamin and Marcel Garvey - with his second intercept try in as many games away from Sixways - helped them secure another RFU Championship scalp and retain to spot at the halfway point.
Hill said: "I thought that was a good performance by us and was much more pleased than the win over Nottingham. This is a tough place to come and London Welsh were smarting after losing to Bedford last week.
"They came out wanting to make amends and get a victory, while we wanted to put in a better performance. So, they'll be disappointed to have lost at home, but I'm delighted we dug deep at the end to get the victory.
"Both teams operated a press defence and they gave us no time on the ball. Their head coach Phil Greening knows that system very well from his time at Wasps and has been coaching it for a long time. We're just starting it after a couple of months, but we disrupted a lot of their ball and got around their press defence.
"When two teams are concentrating on flying up in defence, it is not easy to keep the flow of the game and get across the advantage line.
"Marcel Garvey flew up out of the line to get an interception, which was a very important seven points, but they also got round us on the outside and Josh Drauniniu, their big powerful winger, burst through a couple of tackles to score."
Hill also praised the performance of young fly half Joe Carlisle after he was handed the ten jersey for the biggest test of the season.
"I was pleased with Joe at 10 - I thought he did very well," said the Sixways boss.
"It was a big game for Joe and wasn't easy as I decided to throw him in from the start after having taking a little criticism from one or two quarters. He was very good - he ran the game well and was astute to put us in the right areas at the right time
"We went with Ed Shervington at hooker and Bruce Douglas at three - they both did very well too.
"It was Pat Sanderson's first game back too and he did some very intelligent things. On the whole - although we changed things around and left Greg Rawlinson, Aleki Lutui and Tevita Taumoepeau on the bench to give others a go - we still did well."