** Update Jan 2020 : I've had a fair few people ping me for hints etc. I feel it takes away from previous cachers hard work if I go giving out hints. All I'll say is - if you can work out what you're talking about, everything is right in front of your eyes.
The cache is not at the listed co-ordinates. A reasonably easy puzzle for the experienced puzzle cacher but a little challenging for the novice. Some interesting and very significant history in this area that many might not ever know of.
Your challenge begins..: 03 11 25 14 213 UVWXYZ ABCDEFGHIJKLMNOPQRST
HPRJ AAFJ JRJR JQPL RAFM BWQD IALP TYMA CHDV ASTX TSBS PQEC SRVP ITQM GEJS FPCM PSFQ HOLI BIRM PBIZ UEDT NSMC JWMS CESQ PQEI RJQL BAAB SJAR MIJO SGLR GLFW SENS QAOJ RXBC VLEA IOTJ TTOZ DTEH GFAL FEKM EJTR SIWM VTKF JBMI HLMK KGEB RPQK QAKR OBVH BXOY TROL XHSQ HZFP MGKF EDOP TARD DQJL QECZ PPOT VTNE BXEK OXLM EQDJ HDEN SBOL DQFC RLTL KESR FJWE AOKN UKFO MEOE RDMB RECD HMHA LMQF MIJA RDUE TJIJ WDMS OREP SICG GKIQ MLNK ORZT OQMS TKRD JGEW NAET GDRC MBRR GBMV CCPI BJNU KLTB IQYL QKQF DJPS KXOI JRTY AJOD IMGW SPTD ULIQ FOSR YJQN YOCB HEBW JRNL DLZH KXNB TQLB GRCP KBEP OQEM VQER WPPI PZHC PEDG CDOI TPMT CAKF PFBU FLGA GRLN DWHR FNWI YTHR ESMC QJPY OSKM ZBPA GNJP FQZL QOYJ EQYF SALJ PBSX PEMZ FFCR WILU LXHH EELE NLCG JBOQ JITT FIJI GJSQ JQVF FZEH TLCA CPKN GDEN KTTK TNBC GCTK JAPM KXTP JPZM QIAV RMDC FZDG XBIW JHYN RHFF MGIE RGDL GHGP RLIF GABJ OJGQ YILL LLKK PTPW