BBC head of new comedy Jack Cheshire on producing Hollywood-style visuals at sketch-show prices.

Producing a sketch show with 850 visual effects shots was never going to be easy. We joked that it was the equivalent of three and a half Star Wars. Only funnier. And, obviously, about a 50th of the price.

Director Ben Wheatley and I spent most of the first week on set wondering how a post-production team of freelancers using bought-in PCs could ever compete with Soho's finest. By the end of the shoot we had completed the most challenging and enjoyable few weeks' filming that many of us had ever undertaken. The end results will be seen in The Wrong Door, an innovative new sketch show series soon to be seen on BBC3 and online.

Ben and I had first worked together on Armando Iannucci's Time Trumpet in 2006. Ben had written and directed some items for the show, working with freelance visual effects artists who had mainly come from the video game industry. I suggested scaling the model up to produce TV half-hours, and with a small development budget from Jon Plowman, then BBC head of comedy, The Wrong Door was born.

Our aim was to create a brave new world of comic possibility by devising a genre-busting mix of celebrity cameos, unimaginable locations and impossible visual effects. Within this world, herds of space hoppers and shopping trolleys roam the countryside, robots play tennis and magazines come with a free blow-up boyfriend.

The 10-minute taster DVD spawned a six-part BBC3 series, as well as 13 half-hour scripts for a children's narrative version. To produce these shows, we set up a nine-strong CGI team in our production office, working on high spec Macs and PCs with bought-in effects software.

The CGI team was umbilically linked to our Final Cut edit via a central server, which made for incredibly efficient communication between the edit and the CGI team. This meant that virtually no 3D work was wasted.

Buying in our own edit suite was a good idea. We shot on HD but offlined in DV Pal, conforming each item as it was signed off for the effects team to work on. This was a cheap way of buying a great deal of flexibility into our post-production schedule.

We filmed the show in fortnightly blocks to allow catch-up time for the effects team and prep time for the other departments between each block. I remember striking a deal with the designer that I would make the CGI team blow up the car as long as the art department built me a fibreglass helicopter and a bucket full of dinosaur vomit . “Don't worry, we'll do it in post” became my catchphrase.

It was a tense and thrilling experience to see the cast and crew pull together to make three hours of CGI sketch comedy a possibility. The pressures of both budget and schedule were so intense that every day became a pitched battle against the onslaught of different factors that could potentially derail the whole series.

It was in those daily battles against the clock that the war was won, and it is a credit to the flexibility of people such as production manager Catherine Gosling, first assistant director Chris May, DoP Pete Rowe and our gaffer Martin Taylor, that the show has made it to air at all.

My enduring memory of the shoot will be the bemused look on cast members' faces when the daily cry for a “crew egg” rang out among the production team. With so many CGI stunts and so much of the action being performed by CGI characters, hardly a set-up went by without some member of the production team being required to dive into a locked off shot, or to hide behind a sofa, or lie full length on the floor under a table in order to rattle the props or shake the scenery in some way. We all took it in turns, from runner to director, from third to first AD, from props buyer to producer. Why it was called a crew egg, I can never remember.

I do remember joking in the edit that we had been blessed by the gods of eyeline after several weeks spent with various members of the production team randomly shaking a stick with a tennis ball stuck on the end of it. Personally, I'd never feel safe on set again without one.

The Wrong Door is a BBC Vision production for BBC3. It starts at the end of August. Visit

Jack Cheshire: My tricks of the trade

* A Thermos flask. No matter how good your caterers, having fresh coffee on set at 7am is the single most useful way of keeping yourself popular that I have discovered. And I need about three lidfuls myself to get going.

* Hiking boots. Just keep them in a carrier bag in the boot of your car. No matter where or when you are filming, you will always regret not having them at some point.

* Laptop. Blackberry schmackberry. My laptop is my office and edit away from the office and edit. It's nice to be able to show the crew rough cuts on set. Or storyboards, pictures of your children, the weather forecast for your holiday or the next day's scripts.

* Sat nav. We bought one for our PM at the end of the series because I'm as bored as she is with scrabbling around with the call sheet on the passenger seat at 5am for directions.