Pointing at you above is someone who's been making my life a bit more worth living ever since I can remember, yet I've only just noticed.
For though I've never met her, Elisabeth Sladen has always been just there.
The earliest memory that I have of watching Doctor Who comes from Christmas 1974, when I was three years old. I was watching the end of the omnibus repeat of Planet Of The Spiders, and as I did, was also recalling having seen it six months earlier on June 8th. Though the actual moment in my memory is of the third Doctor finally facing-down the Spider Queen, before and after that scene I would have also been watching Elisabeth Sladen as one Sarah Jane Smith.
In fact, I carried on watching her. It would be almost another two years - until 23rd October 1976 - before she would leave that long-running series.
Leave? Well, no. Although absolutely everyone to regularly feature in Doctor Who has left at some point (present company excepted), Elisabeth Sladen never quite managed it. She kept getting asked back, you see. A lot. I guess she was very popular.
Five years on - 28 December 1981 - I found my ten-year-old self spending some of my school Christmas holidays watching her again in K-9 And Company. This was a stand-alone pilot for a spin-off show. Although the BBC bosses of the day chose not to commision a series, it was paradoxically popular enough for a repeat the following year (which I also watched, and audio-taped). The year after that she was back again for Doctor Who's 20th anniversary story The Five Doctors, in scenes which followed on from the failed pilot.
Of course, I assumed that that would be the final good bye too, but no again. Silly me.
The BBC cassette of Genesis Of The Daleks which my dad got me for my birthday kept getting a lot of listens.
Then on 27th August 1993 - when I was 22 and going out to work - she was back again playing the role in the five-part radio series Doctor Who: The Paradise Of Death.
1993 also saw her second return to the TV show proper in Dimensions In Time.
1995 found her appearing in the direct-to-video spin-off Downtime.
1996 - five more radio episodes of Doctor Who: The Ghosts Of N-Space. Despite Doctor Who's TV cancellation seven years earlier, encountering Sarah again was getting to be pretty ordinary.
So ordinary in fact that by now I was buying these cassettes and then leaving them several years before playing them. After all, I was pretty busy watching all the original TV episodes - including her era - on VHS with my mum and dad each week. When Sarah next recorded new material in 2002 - launching a series of original CD adventures for her character - I admit that I didn't even bother. Hey - Sarah was just not that big a deal any more.
The rest I think you may already know. 2006 - while I was a 35-year-old missionary in New Zealand - found her returning to Doctor Who on TV yet again. Then on New Year's Day 2007 I sat with my family watching the launch of yet another new TV series - The Sarah Jane Adventures. With further new appearances in Doctor Who still to come, the idea of her continuing to play the role for the rest of her life would have sounded like a very welcome idea indeed.
Except that, four days ago, she actually did die.
It's such a shock because she was only 65, but arguably looked half that age. (see picture above) It's such a shock because we didn't even know that she was ill. It's such a shock because my family and I sit round together to watch her 13 times a year, and were looking forward to doing so again this.
It's such a shock because I'm now 40, and have only now noticed that she's been on the wallpaper of my life for as long as I can remember.
Today I read her co-star Tom Baker's tribute, and learnt that plans were afoot for him to record even more Doctor Who audio productions with her!
Incredibly, she was right at the top of her success in the role, despite having decisively left it a staggering 35 years ago.
She must have been doing something very right indeed.
Thank you Elisabeth Sladen for playing the best - the very best - Doctor Who companion of all time. It was incredibly kind of you to let us have Sarah back again for a few more special years.
Well, actually about 35 more.