I'd be willing to call the £10,000 a safety net with the big money still in play, and that is the lowest amount of money on the board that I am willing to call it such on that situation.

There seems to be quite a bit of precedent to establish that amount as the lowest that can be considered as one, given that:
1. Noel claimed that there was virtually a one-box game in Carlton's game back in June 2006 at the stage where he had £100k, £10k, £3k and 5 blues.
2. Wheelchair Peter's game a few games before that where £3k was removed, and Noel claimed it was good (and was applauded), even tho the £3k was the 2nd highest amount on the board, and that the £250k was the only one higher.
3. Dennis encouraging Laura to deal at £19,999 at 5-box because he didn't think that the safety net was strong enough. The next highest amount after the £250k was £5k.
4. Original Gaz no dealing at £8,200 and £35,000, with his two highest amounts being £100k and £10k.
5. The banker's derisory offer of £70,000 to David J with £10k and £250k left, that being a very deflated offer where one would have expected something in the range of £90,000 to £105,000. Compare that to Graeme's £101,000 offer with £5k and £250k at final two, and a £75k offer to Maria with £3k and £250k as her final two.

What is the lowest amount that you are willing to call a safety net involving big money still in play?

£5,000 - not much compared to £250,000, but a lot of money still. Anyway, I'm a Wakeyist. A reckless gambler. I don't need "safety nets".

I'd say it depends on the boards/offers involved. On poor boards, the "oranges" like 1k and 3k, and even the high blues like £500 and £750 an come in extremely useful. But If I was turning down 50k+ on a 250k/something else last pair, I doubt I'd be much happier than £1,000 than with 1p.

Oh god, not you as well.

I'd say £10-15,000 though.

From the start of the game, I'd call £15,000 to £35,000 safety nets.

It depends on what's left during the game. As James1978 said, high blues / low reds can be very worthwhile in a "low money" game but when it comes down to low amounts vs £250k, I think only £20k can be considered a safety net. Also as Goldeneye points out, £10k seems to be pointed to as a safety net on the show itself, and I reckon on most boards, £10k is around about the right value to set for a safety net.

I think I'll go with H - there's probably a better definition in this to do with how much the offer would be affected if it went, or if it stayed but the top amount went, but that's pretty much reflected in the 'volatility' stat really.