21 November 2014 Last updated at 10:09

Mapping UKIP's polling strength

By Christine Jeavans BBC News

Mark Reckless (R) defected from the Conservatives to UKIP

As opinion polls predicted, the UK Independence Party has won the by-election in Rochester and Strood, giving the party its second elected MP.

Conservative incumbent Mark Reckless triggered the contest when he announced his defection to UKIP in September.

In October, another defector from the Tories to UKIP, Douglas Carswell, took the seat of Clacton with almost 60% of the vote.

And in the Heywood and Middleton by-election the same day, UKIP slashed Labour's majority to 617.

Professor of politics at Strathclyde University John Curtice said the most recent result had boosted the party's chances of getting a "significant share of the vote" at the general election in May.

"UKIP will now be able to point to Rochester to say to voters, 'Look, voting for UKIP is not a waste of time, we can actually win,'" he said.

Opinion polling carried out within constituencies in the past year suggests that UKIP has increased its support significantly in many areas since the 2010 general election when it garnered just 3% of the vote nationally.

In the voting intention research, UKIP came top in five locations, including Thanet South in Kent, where party leader Nigel Farage has announced he will be standing.

And the party came second in 22 of the 87 constituencies surveyed, knocking traditional parties into third and fourth place.

UKIP also came second in the other two by-elections in 2014: Newark and Wythenshawe and Sale East.

The full data from the polling, which was mainly carried out by former Tory party chairman Lord Ashcroft's company, reveals UKIP took second place behind the Conservatives in 17 locations and behind Labour in six.

In places where Labour topped the poll, UKIP were mainly in third spot or lower.

Prof Curtice said the October by-election results were "a clear confirmation that UKIP do pose a threat to the votes of all three parties".

He said that the Conservatives were coming under particular pressure from UKIP, but that "all three political parties will be wondering exactly what will face them in six months' time [at the general election].

"All of them are losing votes to UKIP and none of them can be entirely sure what the consequences will be," he said.

By-election results and constituency level opinion polls Dec 2013 - Nov 2014
Constituency currently held by (previously if by-election)	Con	Lab	Lib Dem	UKIP	Other		UKIP place	Source	Date
*All polls are general election voting intention polls except for Folkestone & Hythe which was voting intention if Nigel Farage was local UKIP candidate.
Clacton (CON)	25	11	1	60	3		1st	By-election	Oct 14
Boston and Skegness CON	26	21	2	46	6		1st	Survation	Sep 14
Rochester and Strood CON	35	17	1	42	5		1st	By-election	Nov 14
Thurrock CON	25	29	2	37	6		1st	Ashcroft	Jun 14
South Thanet CON (UKIP leader Nigel Farage will stand here)	30	27	4	32	7		1st	Ashcroft	Jul 14
Camborne and Redruth CON	28	25	11	28	8		1st	Ashcroft	Jun 14
Heywood and Middleton (LAB)	12	41	5	39	3		2nd	By-election	Oct 14
Rotherham LAB	6	48	4	37	6		2nd	Survation	Sep 14
Great Yarmouth CON	33	28	3	32	5		2nd	Ashcroft	Jul 14
North Thanet CON	33	24	6	32	5		2nd	Survation	Sep 14
Walsall North LAB	22	37	5	32	3		2nd	Ashcroft	May 14
Dudley North LAB	25	39	4	29	3		2nd	Ashcroft	May 14
Folkestone and Hythe* CON	35	21	10	28	6		2nd	Survation	Apr 14
St Austell and Newquay LD	30	17	19	27	7		2nd	Ashcroft	Aug 14
Bognor Regis and Littlehampton CON	37	20	11	27	5		2nd	Survation	Dec 13
Torbay LD	34	15	18	27	6		2nd	Ashcroft	Sep 14
Newark (CON)	45	18	3	26	9		2nd	By-election	Jun 14
Eastbourne LD	31	14	24	26	6		2nd	Ashcroft	Sep 14
Great Grimsby LAB	23	37	9	25	7		2nd	Ashcroft	May 14
Newton Abbot CON	39	13	13	23	10		2nd	Ashcroft	Jun 14
North Cornwall LD	39	12	21	23	6		2nd	Ashcroft	Aug 14
Redcar LD	16	45	12	23	4		2nd	Ashcroft	Sep 14
Truro and Falmouth CON	34	20	13	23	11		2nd	Ashcroft	Sep 14
Mid Dorset and North Poole LD	43	11	19	22	5		2nd	Ashcroft	Aug 14
Chippenham LD	40	17	16	20	8		2nd	Ashcroft	Aug 14
Somerton and Frome LD	44	10	19	20	8		2nd	Ashcroft	Aug 14
St Ives LD	37	16	18	20	10		2nd	Ashcroft	Aug 14
Bradford East LD	14	48	14	18	5		2nd	Ashcroft	Jun 14
Harrogate and Knaresborough CON	42	15	17	18	7		2nd	Ashcroft	Jun 14
Solihull LD	41	18	18	18	5		2nd	Ashcroft	Aug 14
Wythenshawe and Sale East (LAB)	15	55	5	18	7		2nd	By-election	Feb 14
Telford LAB	28	38	4	25	5		3rd	Ashcroft	May 14
Corby LAB	32	36	6	24	3		3rd	Ashcroft	Sep 14
Halesowen and Rowley Regis CON	34	35	2	24	4		3rd	Ashcroft	Oct 14
North Warwickshire CON	30	38	3	24	5		3rd	Ashcroft	Jun 14
Waveney CON	29	35	4	24	9		3rd	Ashcroft	Jul 14
Amber Valley CON	34	35	4	23	5		3rd	Ashcroft	Jul 14
Bolton West LAB	30	40	6	22	3		3rd	Ashcroft	Jul 14
Hastings and Rye CON	31	38	4	22	5		3rd	Ashcroft	Sep 14
Ipswich CON	30	36	7	22	6		3rd	Ashcroft	Oct 14
Morley and Outwood LAB	27	39	6	22	6		3rd	Ashcroft	May 14
Sherwood CON	29	40	3	22	6		3rd	Ashcroft	Jul 14
Stockton South CON	32	38	4	22	4		3rd	Ashcroft	Jul 14
Eastleigh LD	34	17	25	21	4		3rd	Ashcroft	Aug 14
Gloucester CON	34	33	7	21	5		3rd	Ashcroft	Oct 14
Morecambe and Lunesdale CON	32	37	6	21	4		3rd	Ashcroft	Jul 14
Nuneaton CON	34	36	5	21	4		3rd	Ashcroft	Oct 14
Plymouth, Sutton and Devonport CON	28	39	4	21	9		3rd	Ashcroft	Jul 14
Carlisle CON	29	41	5	20	6		3rd	Ashcroft	Jul 14
Derby North LAB	26	41	8	20	5		3rd	Ashcroft	May 14
Dewsbury CON	29	40	4	20	7		3rd	Ashcroft	Jul 14
Southampton, Itchen LAB	33	33	9	20	5		3rd	Ashcroft	Aug 14
Berwick-upon-Tweed LD	35	19	22	19	5		3rd	Ashcroft	Aug 14
Broxtowe CON	31	38	4	19	6		3rd	Ashcroft	Jul 14
Halifax LAB	27	41	8	19	5		3rd	Ashcroft	May 14
Lancaster and Fleetwood CON	27	39	3	19	13		3rd	Ashcroft	Jul 14
Taunton Deane LD	35	17	22	19	8		3rd	Ashcroft	Sep 14
Uxbridge and South Ruislip CON	42	28	6	19	5		3rd	Ashcroft	Aug 14
Lincoln CON	33	37	5	18	7		3rd	Ashcroft	Jul 14
Watford CON	30	31	16	18	6		3rd	Ashcroft	Aug 14
Wolverhampton South West CON	30	44	5	18	4		3rd	Ashcroft	Jul 14
Bedford CON	30	39	9	17	6		3rd	Ashcroft	Jul 14
Pudsey CON	33	38	7	17	5		3rd	Ashcroft	Sep 14
Sutton and Cheam LD	36	16	26	17	5		3rd	Ashcroft	Aug 14
Weaver Vale CON	30	44	5	17	4		3rd	Ashcroft	Jul 14
Wells LD	37	16	22	17	9		3rd	Ashcroft	Aug 14
Warrington South CON	35	38	8	16	4		3rd	Ashcroft	Jul 14
Wirral South LAB	30	43	6	15	5		3rd	Ashcroft	May 14
Birmingham, Edgbaston LAB	30	44	4	14	7		3rd	Ashcroft	Aug 14
Brighton, Kemptown CON	32	39	5	14	2	8	3rd	Ashcroft	Sep 14
Enfield North CON	32	44	4	14	6		3rd	Ashcroft	Sep 14
Cardiff North CON	31	38	5	14	5%	Plaid Cymru 5	3rd	Ashcroft	Sep 14
Stroud CON	33	34	8	13	12		3rd	Ashcroft	Jul 14
Hendon CON	35	45	4	12	5		3rd	Ashcroft	Jun 14
Hove CON	34	38	6	12	1	Green 9	3rd	Ashcroft	Sep 14
Crewe and Nantwich CON	33	46	6	11	5		3rd	Survation	Dec 13
Brentford and Isleworth CON	31	47	6	9	7		3rd	Ashcroft	Sep 14
Norwich South LD	19	36	8	17	1	Green 18	4th	Ashcroft	Jun 14
Cheadle LD	35	24	21	15	5		4th	Ashcroft	Aug 14
Oxford West and Abingdon CON	38	22	22	11	7		4th	Ashcroft	Aug 14
Bermondsey and Old Southwark LD	18	39	23	11	8		4th	Ashcroft	Sep 14
Brighton, Pavilion GREEN	18	38	6	10	2	Green 26	4th	Ashcroft	Jun 14
Sheffield, Hallam LD	24	33	23	10	8		4th	ICM	May 14
Cardiff Central LD	22	37	16	10	8	Plaid Cymru 6	4th	Ashcroft	Sep 14
Brent Central LD	14	55	14	9	7		4th	Ashcroft	Jun 14
Cambridge LD	23	38	21	8	10		5th	Ashcroft	Sep 14
Inverness, Nairn, Badenoch and Strathspey LD	12	25	16	7	7	SNP 32	5th	ICM	May 14
Manchester, Withington LD	10	59	15	5	12		5th	Ashcroft	Jun 14
Twickenham LD	34	23	32	5	6		5th	ICM	Apr 14
Hornsey and Wood Green LD	17	49	19	4	11		5th	Ashcroft	Sep 14
Hampstead and Kilburn LAB	32	48	10	3	8		5th	Ashcroft	Aug 14