At its peak, the series had 15 million viewers. The production team opened almost 5,000 letters a day, 20,000 letters a week and upwards of 250,000 letters a year. Jimmy Savile joked that people who misbehaved at the BBC were made to sort the letters as punishment. Roger Ordish said that the production didn't reply to every letter, because the postage would have cost more than the show's entire budget.
There were more than 1,500 'Fix Its' over the course of the series.
Some children apparently thought that Jimmy Savile's first name was "Jim'll", so some letters shown on the programme started "Dear Jim'll".
Internally, the BBC were concerned that the show was providing excessive product placement for corporations.
Allegations surfaced in 2012 that Jimmy Savile sexually abused some of the children who took part in the show, including suggestions that special episodes were devised by Savile in order to gain access to victims. Producer Roger Ordish said, "I didn't see anything and nothing was reported to me", but added that he knew Savile had a "predilection for younger females". Reflecting on his own time producing the show, Ordish added, "It's of no significance really compared to the terrible things that happened to the victims, but in retirement, people say: 'What did you do?'. I'd say: 'I was a BBC producer ... Jim'll Fix It, I did that for 20 years', and you used to get a wonderful reaction. Now it's something I can't mention, you're ashamed of it."