When the EL-JO challenges were published I found that I wasn't pre-qualified for any of them (I prefer challenges like that anyway). I thought that this one would be the easiest for me to achieve however. I hadn't found any Sidetracked caches since 2010 but I'd still managed to get to 18.
It took a couple of months to complete the challenge but all I really had to do was pick them up when I happened to be passing nearby. I finally reached 25 yesterday with the new Sidetracked at Farnham.
We went to pick up the cache this afternoon. It was an easy find, and we left a geogem. We thought the themed playground nearby was nice.
Here are my 25 Sidetracked caches
GC1K150 SideTracked - Dorking West 31 Mar 2009
GC1J2Y5 SideTracked - Dorking 17 Apr 2009
GC1FKT5 SideTracked-Shalford 12 May 2009
GC19JKR Blackwater - SideTracked 25 May 2009
GC1JBGX SideTracked - Dorking North 1 Jun 2009
GC1FQA4 SideTracked - Aldershot 8 Jun 2009
GC1CPZ0 SideTracked - Mottisfont & Dunbridge 31 Aug 2009
GC1JRY5 SideTracked no more - Mottisfont 31 Aug 2009
GC1JKCR SideTracked - Ash Vale 6 Sep 2009
GC1HDXA SideTracked - Deepdene 1 Oct 2009
GC1P5K4 SideTracked - Holmwood 21 Feb 2010
GC23QWQ Sidetracked Guildford 28 Feb 2010
GC1W9QK Sidetracked - Hampton Court 15 Apr 2010
GC29HA9 SideTracked - Chilworth 2 Jun 2010
GC29VFN Sidetracked - Godalming 8 Jul 2010
GC2566H Sidetracked - North Camp 26 Jul 2010
GC2CW0M Sidetracked - Worplesdon 5 Aug 2010
GC2CYPK SideTracked - Wanborough 6 Aug 2010
GC1MFWD SideTracked - Betchworth 28 Feb 2013
GC2RE5G Sidetracked - Christ's Hospital 3 Mar 2013
GC1CTHF Sidetracked - Gomshall 4 Apr 2013
GC23X29 Sidetracked London Road (Guildford) 9 Apr 2013
GC482WG Sidetracked Brookwood 11 Apr 2013
GC1YVGP Sidetracked - Horsley 2 May 2013
GC4B0AZ SideTracked - Farnham 5 May 2013
More details here.