I took an FIS from London Information a couple of weeks ago and got too close to Stansted's air space. London called me and said that "they" (presume Essex Radar) had "been on the phone" and asked me to check my navigation.
If I'd not been receiving the FIS, I wouldn't have received the warning, which appears to have been completely within the rules as it was (apparently) Essex Radar that had interpreted and acted upon the radar trace.
It proved the value of the FIS to me. Even professional pilots with big aeroplanes full of computers land their aircraft at the wrong airports, so with the best will in the world, the amateur like me is going to make mistakes.
Thank you London Information & Essex Radar.