Is there such a thing as Intrusive-L (as opposed to Intrusive-R)?
Short answer
Yes, there are varieties of English that use linking and intrusive l in a similar way to how other non-rhotic varieties use linking and intrusive r.
- spa /spa:/
- is /ɪz/
- the spa is /ðə spɑ:r ɪz/ "the spar is" (intrusive r)
- the spa is /ðə spɑ:l ɪz/ "the spal is" (intrusive l)
The examples above show some similarity between linking r and linking l. However, the two are not necessarily quite as similar as they might seem.
Full answer
There has for some time now been interest in the occurrence of intrusive-l a feature of some varieties of English from the north-east of the US. Strangely, although now reasonably well-documented, it is more often seen discussed in the literature because of the light it may throw on the phonological structure of intrusive-r in other varieties, whose distribution it follows in important respects.
Below is a relevant excerpt from an already old paper: Gick, B. (1999) 'A gesture-based account of intrusive consonants in English'. Phonology 16, pp. 29-54:
3 Intrusive l and other l phenomena
3.1 l-vocalisation, linking and intrusion
The intrusive l (see (5)) is a surprisingly widespread phenomenon, showing patterns similar to those seen in the intrusive r. Its use has been primarily identified with working class and rural dialects in Pennsylvania, Delaware and other areas of the northeastern United States, though it has been reported in all other regions of the country except the Northwest. The few references to the intrusive l to date have all been made in unpublished works (Gick 1991, 1997, in preparation, Miller 1993).
(5) The intrusive l of south-central Pennsylvania
I draw [dɹɔ:ʁ] --> 2 I’m drawing [dɹɔ:lɪŋ]
the bra [bɹɑ:] --> 2. the bra is [bɹɑ:lɪz]
The intrusive l, like the intrusive r, can be described as the presence of a non-historical consonant between two vowels, the first of which belongs to a limited set always including /ɔ/, and very rarely /a/ and /ə/ as well. Also reminiscent of the intrusive r is the hierarchy of related processes associated with l-intrusion, which is fixed in the familiar order of vocalisation, linking and intrusion.
As with r, the historical vocalisation of some pre-consonantal coda /l/'s is evident from orthographic artefacts in such words as half, salve, salmon, talk, calm, folk, etc. In some dialects, however, this process has extended to all coda /l/'s (e.g. drawl [dɹɔ:l]). Ash (1982a) says of certain Philadelphia-area dialects : 'the vocalisation of /l/ results from the loss of contact between the tongue and the palate', a description of l-vocalisation that is well documented for many English dialects (Giles & Moll 1975, Kahn 1976 : 58, 104—105, Ash 1982a, b, Hardcastle & Barry 1989, Brow-man & Goldstein 1995 : 26—27, Narayanan et al. 1997 : 1070).
Again parallelling the patterns of r, in most /l/-vocalising dialects, a brighter allophone of /l/ (one involving a greater tongue tip constriction, among other things) may be heard in intervocalic positions (e.g. drawling [dɹɔ:lɪŋ]). That is, most dialects with vocalisation of/l/ also show linking (see Ash 1982b for an exceptional dialect).
Finally, in some dialects having both vocalisation and linking, as with intrusive r, an [l] can appear intervocalically when a vowel-final word or stem is followed by another vowel. Also similar to the r case, as stated above, the intrusive l may appear following only a very limited set of vowels.
[pp. 35-36]
Gick's 2002 paper The American Intrusive l is downloadable here, if you have an Academia.edu account, or sign up for one. It's free.
I was not aware of /l/ being ever used in the way /r/ is in RP to link two words ending and beginning with a vocalic sound respectively until I read Araucaria's answer. In any event, it might be worth quoting J. C. Wells at length on so-called Bristol l, even though it is not a sandhi phenomenon.
Here is the relevant excerpt from Accents of English (Vol.2, pp.344-345):
Bristol is the home of another famous consonantal characteristic, Intrusive /l/. This consists in the addition of /l/ to words which would otherwise end in /ə/(e.g. banana, tomorrow: i.e. words belonging to the standard lexical set commA, or those ending in RP unstressed /əu/; but those belonging to lettER, of course, have /-ər/). This makes area a homophone of aerial [ˈɛ:ɹjəɫ]. Intrusive /l/ is not a sandhi phenomenon: it can apply equally to a word which is sentence-final or in isolation, and it varies allophonically between clear and dark according as the following segment is or is not a vowel.
It has given rise to many jokes. Bristol is 'the only city in Britain to be able to turn ideas into ideals, areas into areals, and Monicas into monocles', where a father had ' three lovely daughters, Idle, Evil and Normal', where a local girl learning to dance was heard to say 'I can rumble and tangle' (quotations from Dirk Robinson, Son of Bristle. Bristol: Abson Books). Thus derided and stigmatized, Intrusive /l/ seems always to have been a pretty local phenomenon, not occurring beyond the boundaries of Avon; even within them it is by now quite rare. Its origin must presumably lie in hypercorrection after the loss of final /l/ after /ə/, a hypothesized [ˈæpə] for apple. When the /l/ was restored under pressure from standard accents, it was added analogically to all words ending in [ə]. Bristol itself was once Bristow.
Wells has a blog entry on this (http://phonetic-blog.blogspot.com/2010/01/bristol-liquids.html#comment-form). Some of the comments, presumably by speakers of American English, further remark on the phenomenon.
One commenter writes the following:
(…) In passing, thought I'd mention that I once had a client from northern New Jersey who could not say idea without turning it into ideal. Came out of left field - it's not a feature of the local accent to my knowledge.
To which another one responds:
I've heard that quite a lot actually. I used to pronounce "idea" as "ideal" when I was younger and some of my cousins did too (we're American, btw). I remember how our grandma would remark on that and tell us how it was "wrong". She probably thought it was our parents' fault. It seems like a pronunciation that some people (like me) "grow out of" and others (like your client) don't. I don't why that happens, but it does.