What is transmitting this radio signal @~110.515MHz and for what purpose?
Well, the SDR dongle paid off - mystery solved.

It turns out, the signal was actually at 153.2MHz, but was somehow breaking through into 110.515MHz on my handheld scanner.

The signal originates from a high power pager transmitter using the FLEX protocol. As this is plain text, I decoded some of it using an excellent open source application called PDW, and have listed it below for reference and general interest (sensitive information has been redacted!).

  0074162  23:12:31 30-06-15 FLEX-A    ALPHA   3200   31:Jun 30 23:11 Trim Line 2 L359 Error Check 01 Override 010312 30-JUN-2015 23:10:49
  0000002  23:12:56 30-06-15 FLEX-A    ALPHA   3200   THIS IS A TEST PERIODIC PAGE SEQUENTIAL NUMBER  0069
  0121518  23:12:59 30-06-15 FLEX-A    StNUM   3200   31948    
  1734139  23:13:01 30-06-15 FLEX-A    ALPHA   3200   61:Jun 30 23:12 Term B  Page-fail test
  1756286  23:13:24 30-06-15 FLEX-A    ALPHA   3200   PIN 6840 PLS CALL DSCC ON 08457 500***
  0118459  23:13:46 30-06-15 FLEX-A    ALPHA   3200   20150630 23:13 boc1web02.servstream.com: conn CRITICAL ALERT
  0000002  23:14:03 30-06-15 FLEX-A    ALPHA   3200   THIS IS A TEST PERIODIC PAGE SEQUENTIAL NUMBER  0070
  1734139  23:14:09 30-06-15 FLEX-A    ALPHA   3200   62:Jun 30 23:13 Term B  Page-fail test
  0076963  23:14:29 30-06-15 FLEX-A    ALPHA   3200   55:Jun 30 23:13 23.13hrs Zone 14 L550 down 15 Mins maint in attendance FROM: GB50-AFENNEL3
  0074162  23:14:46 30-06-15 FLEX-A    ALPHA   3200   32:Jun 30 23:13 Trim Line 2 L359 Error Check 01 Override 010312 30-JUN-2015 23:12:42
  0074179  23:14:48 30-06-15 FLEX-A    ALPHA   3200   19:Jun 30 23:13 Z2A LH Stn 200  Main Call 30-JUN-2015 23:13:22
  0074194  23:14:50 30-06-15 FLEX-A    ALPHA   3200   56:Jun 30 23:13 23.13hrs Zone 14 L550 down 15 Mins maint in attendance FROM: GB50-AFENNEL3 FROM: GB50-AFENNEL3
  0107291  23:14:50 30-06-15 FLEX-A    StNUM   3200   2422085  
  0074076  23:14:50 30-06-15 FLEX-A    ALPHA   3200   60:Jun 30 23:13 Fac 1670 More than 20 I/P on conv 30-JUN-2015 23:11:30
  0086317  23:14:52 30-06-15 FLEX-A    ALPHA   3200   36:Jun 30 23:13 Dodo Panel 23 Entry Movement Alarm 000065 30-JUN-2015 23:12:03
  0000002  23:14:56 30-06-15 FLEX-A    ALPHA   3200   THIS IS A TEST PERIODIC PAGE SEQUENTIAL NUMBER  0071
  0067432  23:14:59 30-06-15 FLEX-A    ALPHA   3200   71:Jun 30 23:14 Water Test WATER TEST SUMP LEVEL HIGH 001215 30-JUN-2015 23:14:46
  1754937  23:15:16 30-06-15 FLEX-A    ALPHA   3200   'Adv' 7440298 30/06/2015 23:08:33 tight chest, struggling to breathe, EMAS ETA 11 mn, Priority RED2 Age 59 Incident area - KETTERING ** ****** ** NN16 ***
  0067432  23:15:22 30-06-15 FLEX-A    ALPHA   3200   72:Jun 30 23:14 Skid RETURN PROBLEM CHECK SKID RETURN Tested o.k. 30-JUN-2015 23:12:25
  1734139  23:15:24 30-06-15 FLEX-A    ALPHA   3200   63:Jun 30 23:14 Term B  Page-fail test
  0086317  23:15:44 30-06-15 FLEX-A    ALPHA   3200   39:Jun 30 23:14 Dodo Panel 6 P&amp;F Emergency Stop relay 125KN1 - 400301.08 30-JUN-2015 23:13:32
  1734136  23:15:46 30-06-15 FLEX-A    ALPHA   3200   19:Jun 30 23:14 Term A  Page-fail test
  0067154  23:15:50 30-06-15 FLEX-A    ALPHA   3200   Fr:nocteam Su:Escalate PQV-73575-125 Tx:Auto escalation of ticket (3 hour rule) Ticket: PQV-73575-125 Queue: VelociX Date raised: 2015-06-30 20:11:27 Subject: ANTEL New asset request
  0117556  23:15:54 30-06-15 FLEX-A    ALPHA   3200   PLS CALL DUTY OFFICE
  0000002  23:16:03 30-06-15 FLEX-A    ALPHA   3200   THIS IS A TEST PERIODIC PAGE SEQUENTIAL NUMBER  0072
  0111087  23:16:07 30-06-15 FLEX-A    StNUM   3200   71301    
  0118459  23:16:16 30-06-15 FLEX-A    ALPHA   3200   20150630 23:15 boc1backup.siops.net: msgs CRITICAL ALERT
  1734139  23:16:31 30-06-15 FLEX-A    ALPHA   3200   64:Jun 30 23:15 Term B  Page-fail test
  0074208  23:16:37 30-06-15 FLEX-A    ALPHA   3200   69:Jun 30 23:15 Warning : BODY DELIVERY STN 1 OVERCYCLE * BD SKID BD SKID (52)
  1734136  23:16:54 30-06-15 FLEX-A    ALPHA   3200   20:Jun 30 23:16 Term A  Page-fail test
  0074221  23:16:54 30-06-15 FLEX-A    ALPHA   3200   09:Jun 30 23:15 Warning : BODY DELIVERY STN 1 OVERCYCLE * BD SKID BD SKID (53)
  0120075  23:16:56 30-06-15 FLEX-A    ALPHA   3200   PLS CALL 12F ON 42848 2ND CALL
  1734139  23:17:39 30-06-15 FLEX-A    ALPHA   3200   65:Jun 30 23:16 Term B  Page-fail test
  1756806  23:17:41 30-06-15 FLEX-A    ALPHA   3200   PLS CALL ***** ***** - ADDENBROOKES ON 01223 257 ***
  0121619  23:17:42 30-06-15 FLEX-A    ALPHA   3200   P2 TS 3170
  0074162  23:17:46 30-06-15 FLEX-A    ALPHA   3200   34:Jun 30 23:16 Trim Line 2 L359 Error Check 01 Override 010312 30-JUN-2015 23:15:30
  1728604  23:18:05 30-06-15 FLEX-A    ALPHA   3200   41:Jun 30 23:17 ****** ******** 07711 239 ***
  0067432  23:18:07 30-06-15 FLEX-A    ALPHA   3200   73:Jun 30 23:17 Conv 11 Conv 1 Starved Load stn Blocked 30-JUN-2015 23:14:55
  0090980  23:18:07 30-06-15 FLEX-A    ALPHA   3200   30/06/2015 23:15:02 INC 14517765 ETFR Countess of Chester Hospital Chester Cheshire -, THE COUNTESS OF CHESTER HEALTH PARK, CHESTER, CH2 *** Male 25Y ProQA Overrid
  0090980  23:18:09 30-06-15 FLEX-A    ALPHA   3201   [Continued message - Fragment #2]den - Call Escalated GRD 340129 368274
  0067432  23:18:09 30-06-15 FLEX-A    ALPHA   3200   74:Jun 30 23:17 Conv 11 Conv 1 Starved Load stn Blocked 30-JUN-2015 23:14:55
  0067432  23:18:11 30-06-15 FLEX-A    ALPHA   3200   75:Jun 30 23:17 Water Test BOOTH 2 LOW / HI WATER PRES30100230 KU-.2N1u013 (?E4
  0118459  23:18:11 30-06-15 FLEX-A    ALPHA   3200   30 23:17]X[??Xns01.siops.net: dnPyt7xyICAL ALERT
  0114910  23:18:13 30-06-15 FLEX-A    ALPHA   3200   40:Jun 30 23:17 PLS CALL LEAH ON EXT 31505
  0119227  23:18:16 30-06-15 FLEX-A    ALPHA   3200   42:Jun 30 23:17 PLS CALL DUTY NURSE 020 7561 ****
  0120151  23:18:27 30-06-15 FLEX-A    ALPHA   3200   PLS COME TO CAVENDISH UNIT
  0118459  23:18:46 30-06-15 FLEX-A    ALPHA   3200   20150633 27z1b"bocm$n:th4Cp
  1743989  23:18:46 30-06-15 FLEX-A    ALPHA   3201   [Continued message - Fragment #2]
                                                          WN i$*CHER 01226 872 199 REajlFE AT POST OFFICE WONPi OCK AND IS WIDE OPEN*?f
  1756806  23:18:48 30-06-15 FLEX-A    ALPHA   3200   PLS CALL ***** ***** - ADDENBROOKES ON 01223 257 ***
  1734139  23:18:54 30-06-15 FLEX-A    ALPHA   3200   66:Jun 30 23:17 Term B  Page-fail test
  0000002  23:18:56 30-06-15 FLEX-A    ALPHA   3200   THIS IS A TEST PERIODIC PAGE SEQUENTIAL NUMBER  0075
  1734136  23:19:16 30-06-15 FLEX-A    ALPHA   3200   22:Jun 30 23:18 Term A  Page-fail test
  0067432  23:19:22 30-06-15 FLEX-A    ALPHA   3200   76:Jun 30 23:18 Conv 11 Conv 1 Starved Load stn Blocked 30-JUN-2015 23:16:09
  0067432  23:19:24 30-06-15 FLEX-A    ALPHA   3200   77:Jun 30 23:18 Conv 11 Conv 1 Starved Load stn Blocked 30-JUN-2015 23:16:09
  0076517  23:19:26 30-06-15 FLEX-A    ALPHA   3200   38:Jun 30 23:18 Conv 21 Check Zone Start Pulse Count 30-JUN-2015 23:19:15
  0114375  23:19:26 30-06-15 FLEX-A    ALPHA   3200   30:Jun 30 23:18 Conv 21 Check Zone Start Pulse Count 30-JUN-2015 23:19:15
  0076956  23:19:27 30-06-15 FLEX-A    ALPHA   3200   97:Jun 30 23:18 Conv 21 Check Zone Start Pulse Count 30-JUN-2015 23:19:15
  1734139  23:20:01 30-06-15 FLEX-A    ALPHA   3200   67:Jun 30 23:19 Term B  Page-fail test
  0000002  23:20:03 30-06-15 FLEX-A    ALPHA   3200   THIS IS A TEST PERIODIC PAGE SEQUENTIAL NUMBER  0076
  0074162  23:20:09 30-06-15 FLEX-A    ALPHA   3200   36:Jun 30 23:19 Trim Line 2 L359 Error Check 01 Override 010312 30-JUN-2015 23:18:09
  0114910  23:20:13 30-06-15 FLEX-A    ALPHA   3200   41:Jun 30 23:19 PLS CALL **** ****** ON EXT 34335
  1734136  23:20:31 30-06-15 FLEX-A    ALPHA   3200   23:Jun 30 23:19 Term A  Page-fail test
  0102150  23:20:33 30-06-15 FLEX-A    StNUM   3200   0778
  0000002  23:20:56 30-06-15 FLEX-A    ALPHA   3200   THIS IS A TEST PERIODIC PAGE SEQUENTIAL NUMBER  0077
  1734139  23:21:09 30-06-15 FLEX-A    ALPHA   3200   68:Jun 30 23:20 Term B  Page-fail test
  0076517  23:21:14 30-06-15 FLEX-A    ALPHA   3200   39:Jun 30 23:20 Conv 21 Check Zone Start Pulse Count 30-JUN-2015 23:21:02
  0119626  23:21:18 30-06-15 FLEX-A    ALPHA   3200   34:Jun 30 23:20 Conv 21 Check Zone Start Pulse Count 30-JUN-2015 23:21:02
  0102150  23:21:18 30-06-15 FLEX-A    StNUM   3200   0775899****** 
  0076956  23:21:20 30-06-15 FLEX-A    ALPHA   3200   98:Jun 30 23:20 Conv 21 Check Zone Start Pulse Count 30-JUN-2015 23:21:02
  0200905  23:22:34 30-06-15 POCSAG-3  ALPHA   1200   23:22-98 30/06/2015 23:20:18 INC 14517787 31C02 ************, ELLESMERE PORT, CH65 *** Male 64 Years M PASSING OUT GRD
                                                      340506 375692
  0334410  23:23:50 30-06-15 POCSAG-3  ALPHA    512   23:22-41 C2 Incident Allocated, Locn: *****, GREENACRES CARE CENTRE, TEARN ROAD, PL35JF, , AZ:, CAD:300615005110, ChComp:
  1508907  23:23:51 30-06-15 POCSAG-4  ALPHA    512   CH3A 512
  0273040  23:24:04 30-06-15 POCSAG-4  ALPHA   1200   30/06/2015 CH3A
  0269168  23:24:20 30-06-15 POCSAG-3  ALPHA   1200   23:24-10 30/06/2015 23:22:15 INC 14517792 10D02 ***********, NEWBOLD ROCHDALE ROCHDALE, OL16 *** Female 24 Years
                                                      MIGRAINE - FEELS SICK GRD 390789 412576